To what extent are both major parties ideologically distinct?

This is a nice question merely comparing the similarities and differences between the Republican Party and Democrats, and evaluating whether or not both parties are completely ideologically distinct. The likely argument should be that both parties are ideologically distinct given the increase in polarisation in recent years with both parties moving further away from the centre ground, the Democrats are an established liberal party while the Republicans are a socially and fiscally conservative party.

Not ideologically distinct (Not polarised)	Ideologically distinct (polarised)
FOREIGN POLICY. Under the Obama administration American foreign policy remains ultimately unchanged and just like with his predecessor Republican president, America continues to play this role of a world policeman under the Democrat President. During Obama’s first term there was a surge in troops in Afghanistan, being increased by around 80% in total. Recently we’ve also witnessed the US getting involved in the Ukraine crisis, again illustrating this world policeman role. Obama got involved in the 2011 Libya attacks. There is a lot of agreement between the GOP and Democrats on what to do in the middle east with ISIS running around bombing stuff à Obama has began intensifying efforts in terms of airstrikes against ISIS, the number of people killed using drone strikes under the Obama administration exceeds 2,400 à even sent in some ground troop for special operations against ISIS. Both parties are working together in the fight against the Islamic State and also in recent events there has been a lot of evidence of bipartisanship from both parties in the passage of the USA Freedom Act, curtailing certain provisions of the PATRIOT Act which enable the NSA to spy on American citizens phone records. This bipartisanship was evident from the newer generation of GOP Senators and House members who were elected following 9/11 and have sided with the Democrats in opposing the renewal of certain provisions of the Patriot Act.	Unlike their traditionally hawkish counterparts, the Democrats have in fact adopted a very different stance towards foreign policy in recent years à less interventionist and focusing directly on multilateralism in the form of diplomacy instead as illustrated by diplomatic efforts between John Kerry and key Russian figures on the Ukraine crisis and in 2013 peace negotiations regarding the Syria civil war between Kerry and Bashar al-Assad. While the Democrats have favoured multilateralism the Republicans have been criticising the Democrats efforts on foreign policy consistently e.g. saying that Democrats foreign policy has been a ‘disaster for America’ because Obama initially downplayed the threat of ISIS and his response to the threat was slow. Republicans like Rick Santorum want to deploy 10,000 American troops and similarly Scott Walker and Rick Perry also favour some form of combat missions on the ground. The Democrats have indeed been more ‘dovish’ on foreign policy and the Republican party seems dominated by neo-conservative values, which have reinforced hawkish sentiments within the party.
BIG GOVERNMENT+ECONOMY. Over the past few decades both parties have become increasingly ideologically similar in terms of the whole principle of ‘big government’, which was particularly seen from Bush’s stance towards Federalism. Bush campaigned as a ‘compassionate conservative’ whereby America witnessed the expansion of the federal government. The most notable measure by Bush was the No Child Left Behind Act – which was a bipartisan measure between the GOP and Democrats – the package of measures established national criteria for school performance, national rules for testing were established, etc and was the biggest expansion of federal influence in education since the 60s (this was seen at the time as the govt taking away the role of states in education) à this was known as coercive federalism. Under Bush federal spending increased from a total of $1.62 trillion to $.179 trillion by 2007. He also made expansions to Medicare, signing a $534 billion prescription drug benefit known as Medicare Part D, which was also continued by the Democrats with Obamacare. This expansion of federal government is very similar to Democrat ideology, highlighting the similarities between the Democrats and Republicans. Blue Dog Democrats in the GOP have been active in recent years, they’re fiscal conservative wing of the Democratic party and align themselves with the Republicans on economic policy and played an instrumental role blocking the public option.	Both parties are without a doubt ideologically distinct in the area of the scope of federal government with regards to healthcare reform and overall ‘big government’. The days of compassionate conservatism from the Bush era are over and with the emergence of the Tea Party which has acted as a polarising force within the GOP, the Republican party have moved further to the right and are now more fiscally conservative than ever and the Tea Party are forcing Republicans to toe a specific policy line in which they’re refusing all compromises with the Democrats which was best illustrated by the issue of Obamacare. While the Democrats support Obamacare, which would essentially expand the scope of federal government by giving them more control over the healthcare ‘system’ (if you can call it that) and taking it away from the states. The Republicans on the other hand, have sought to oppose Obamacare at all costs as seen by the fact that in 2010 every single House Republican voted against it – Obamacare according to them is an infringement on states rights and reinforces this whole rhetoric of ‘government creep’. The most convincing evidence that the two parties are ideologically distinct come from the 2013 government shutdown which illustrated how polarised both parties have become – the GOP opposed proposed tax hikes in order to further fund Obamacare, which eventually led to a government shutdown. Moreover, Democrats passed an economic stimulus package in 2009, which was opposed by the GOP. President Reagan established the Republican Party as a fiscally conservative party and the Tea Party have enforced such sentiments as illustrated by the recent passage of the 2015 budget, introducing $5.3 trillion in cuts which will make it easier to repeal Obamacare. Blue Dogs have declined in recent years with only 14 House members remaining.
IMMIGRATION. One area of immigration reform which both Democrats and Republicans seem to agree on is the issue of border control and security. Many Republicans believe that the border needs tighter control and security to prevent more illegal from getting in and the Democrats seem to also agree, e.g. Obama worked with Congress in 2010 to expand spending on border security by a total of $17 billion. Moreover, after the 2012 presidential election it turned out that 75% of Latinos voted for Obama – a significantly low portion (in contrast to Obama) voted for Romney, probably because of his tough stance on immigration reform, which alienated many voters. Since then, the Latino Vote is becoming increasingly important (atm its around 54m, making Hispanics the largest minority group) and therefore GOP are becoming more supportive of immigration reform. Marco Rubio, a hopeful 2016 presidential candidate, is one Republican who has supported a path to citizenship in the past. Moreover, there have been bipartisan measures between Democrats and Republicans in passing reform such as the Gang of 8 Bill (which failed, was led by Marco Rubio and Chuck Schumer). Republicans for Immigration Reform is a Super PAC aims to push forward comprehensive reform agenda in the GOP. Jeb Bush has also admitted that the GOP can’t deport 11m so its time they embraced immigration reform, accusing the GOP of ‘bending with the wind’ on immigration	Both parties and without a doubt ideologically distinct on immigration policy as seen in recent years. The Democrats are more lenient on immigration reform, seeking to introduce comprehensive immigration reform because it is the ‘common sense’ thing to do as deporting 11 million illegal immigrants is unrealistic. Obama has working towards making illegal immigrants feel more free so they can ‘come out of the shadows’ as seen from Obama’s executive order which has sought to help 5 million illegal immigrants. Moreover, more Democratic attempts have been seen from the introduction of DACA, which allows individuals who came before 2007 and before they were 16 years old to stay in the US. The Republicans on the other hand have adopted a tough stance on immigration reform and have tried to resist all Democrat attempts at passing immigration reform, such as filibustering the DREAM Act in 2010 and were outraged at Obama’s executive order which they viewed as being the actions of a king or an emperor (John Boehner) and some were so outraged they said Obama’s actions were illegal (‘executive overreach’), the GOP also attempted to scrap the executive order by refusing to fund the Department of Homeland Security earlier this year. The Republicans see comprehensive immigration reform as a way of rewarding people, by granting amnesty, who have committed a crime by illegal entering the US and so have opposed any form of a path to citizenship. In the Republican dominated state of Texas, a federal court has recently refused to allow Obama’s executive order to take effect immediately – putting it on hold instead. GOP dominated states have adopted tough anti-immigration measures like Arizona SB 1070
SOCIAL POLICY. With the legal tide on gay marriage in the US changing (legal in 36 states) and gay marriage becoming an increasingly accepted thing across the world and in the US and failures endured by social conservatives such as Hollingsworth v. Perry and in US v. Windsor, the GOP is struggling seriously with adapting to the changing shift. GOP are afraid of alienating young voters (who tend to support gay marriage) but are also afraid of alienating its core evangelical Christian base (who oppose gay marriage) but some have come out in support such as Jeb Bush. Democrat inability to pass gun control = GOPish? + Bill Clinton Don’t Ask, Don’t Tell	Just like with economic policy, Reagan also established the GOP as a socially conservative party during the 1980s while since around the 1960s the Democrats have been established as a liberal party. So, both parties remain completely ideologically distinct parties. The Obama administration in recent years been promoting more liberal causes and introduced liberalizing legislation. For instance, the Democrats continued to support gay marriage and have expanded gay rights through the repeal of Don’t Ask, Don’t Tell, undoing Clinton’s policy. The Republicans on the other hand continue to firmly oppose immigration reform as seen from the ongoing Obergefell v. Hodges case in which key Republican figures have spoken out against gay marriage such as Marco Rubio who thinks its ridiculous to assume that gay marriage is protected in the constitution.