In what can be descried as “the great compromise,” the “left” will generally get its way on cultural/social issues (abortion, diversity, immigration, gay marriage, social security, etc.) and the “right” will get its way on foreign policy (defense spending, interventionism) and economics (tax cuts). However, immigration is an issue that splits the right (in spite of the election of Trump, 45% of republicans still support or are indifferent to immigration), so this makes it significantly harder for Trump to make progress on immigration than defense spending, foreign intervention, or tax cuts, and is why, despite promises of a wall during the campaign, it’s unlikely to ever be built.
However, this compromise tends tobe lopsided. The ‘left’ historically has had more successes with policy than the ‘right’. Obama created Obamacare, ended the ‘Don’t Ask, Don’t Tell’ policy, oversaw the repeal of the Defense of Marriage Act, bailed-out domestic automakers, passed a large but ineffective economic rescue plan, and so on. Regarding Trump, however, progress has been slower, with smaller and fewer domestic policy wins than under Obama. Little progress on immigration thus far (much of it is just threats and tentative ideas, not actual signed legislation, orders, or policy; Trump backtracked on ‘family separations’ after negative press, similar to him backtracking on the ‘travel ban’ after getting bad press); a big tax cut (the only successful legislation thus far); tariffs on China that have not reduced the trade gap and are economically immaterial; some sanctions on Russia and Turkey for no good reason but as an arbitrary exercise of power, and, similar to Obama, more airstrikes on Syria for supposed chemical weapons.
The ‘right’ is also split regarding possible censorship and collusion by social networks. Despite complaints and evidence of systematic and coordinated social media suppression and censorship of right-wing views and businesses, there is not much impetus by republicans–in site of control of all three branches of government–to do anything, because of the issue of freedom of association and ‘free markets’, and also that political orientations are not protected class. Trump can tweet about tech censorship, but no action is taken (not that there is much that he can do), and it’s soon forgotten as if nothing happened. Same for complains about Amazon costing the USPS money, high drug prices, companies moving factories overseas, and so on. So because the ‘right’ has much less cohesion than the ‘left’ on most issues (save for tax cuts and defense), this means the ‘left’ can expect to have more victories as we saw under Obama. Making matters worse, as part of the compromise, the ‘right’, given enough time, will cave-in to the ‘left’ on social issues. For example, Roberts and McCain caving-in on Obamacare.
Generally, the ‘right’, unlike the ‘left’, cares more about the position of power than policy. The left however seeks to use the power to reshape society, but the right wants to get their guys in power but then not do much afterwards, leaving the issues up local governments and states and preferring a more incrementalist approach (except for matters of nation security, such as terrorism).
As evidence of this compromise, Trump recently signed a massive $850+ billion spending bill for defense and social programs, avoiding a potential government shutdown. Securing funding for the wall will be much harder, and depending on the outcome of the midterms, may not succeed. Even if some funding is secured, is no guarantee construction will actually begin, which is yet another hurdle. If Trump loses, then the wall will certainty be scrapped.