Based on everything obvious to the normal observer, the American polity is in a bind — the Democratic Party and Republican Party are each caught in their own vicious cycles and are neither in a good shape to resist Trump’s onslaughts on middle-class economic well-being.
State of the Republican Party:
In the pre-Obama era, the GOP distracted its middle class voters with social issues while undermining them on economic issues. Right wing propaganda got GOP's middle class voters so enraged over, for instance, defense of marriage, abortion, evolution, and the role of religion in public life, that they voted for the rich donor class's agenda, namely, for undermining 'entitlement' programs, ending infrastructure spending, increasing tax cuts, dismantling financial regulation, and promoting corporate-friendly trade policy.
The rich donor class was happy achieving its economic agenda, ideological conservatives were happy achieving their ideological agenda, GOP politicians were happy being conduits&middlemen. The middle class voter got a warm fuzzy feeling though he was voting to destroy his own economic interests.
Most recently, Barack Obama came along and began bolstering the middle class’s economic interests on a number of things. Social issues of the past became less controversial. So, racial hatred directed at Obama became the new warm fuzzy feeling that GOP delivered via right wing propaganda to the middle class voter. The rich donor class bided its time.
Meanwhile, the GOP political class got itself into a hostage situation via gerrymandering and donor dependence. If a GOP politician showed any flexibility or moderation on a given issue, he had no new voter pool to support him(having gerrymandered them out of his district) and besides, the rich donor class would just switch their funding from him to a new primary opponent.
Then came Trump, who is the absolute master of giving middle class voters warm fuzzy feelings on every issue - mostly via inciting racial, religious and cultural dislike of fellow Americans, and by inciting rage at the economic trickery practiced by politicians and their rich donors.
Trump did not incite voters’ rage at the above-described GOP ecosystem so much as at Obama, Hillary Clinton and the Democrats, who were designated as the sources of all middle class evil and misery, and the middle class voter voted for Trump and the GOP, accordingly.
But there is now no Obama or Clinton to stand in as GOP enemy and the Democrats are in minority in Congress. The rich donor class would back Trump if they knew that he would deliver their economic agenda. GOP politicians are in a bind- their voters' economic interests and their rich donor class's economic interests are as always, at odds, though neither they nor their voters will admit it.
GOP politicians can't oppose Trump, who is a one-man alt-right propaganda machine; they are tied to their rich donors’ agenda of tax cuts and destroying government programs and regulations, and not having Obama or Clinton to bash, they don't know what to say to their voters.
State of the Democratic Party:
In contrast, the Democratic Party should be in good shape to resist Trump since the Democratic Party's economic agenda has been best suited to middle class economic interests. The Democrat economic agenda appears to be a mix of pro-growth and progressive ideas in spite of being corporate-driven on a number of things and having a rich donor class of its own.
But its pro-middle class economic agenda is a useless advantage because after the election, middle class voters are not hearing about it. The Democratic Party has no charismatic leader, no effective propaganda apparatus, and its non-inciteful messaging doesn't give voters a warm fuzzy feeling.
The Democrats are also in a vicious cycle of losing ground. By losing elections, they lose not just power but lose ground with their donor class and their visibility to the public. By not propagating a coherent economic message on the hot button issues of each Trump day, they are losing the propaganda war to Trump on middle class economic interests.
For instance on trade and immigration, Trump has fudged issues by conflating cultural, religious, racial supremacism with economic success. He declares that immigrants are criminals and parasitic to the economy, that trade deals and economic policies were made by traitorous and venal politicians, that Obamacare is an unmitigated disaster, that those protesting its repeal are not Republican voters, that Democrats care more about identity politics than sound economic policies.
Actually Trump is most vulnerable to Democrats on the economic arguments underlying his incendiary polemic. Trade and immigration policies, if done right, can bolster the middle class with good jobs, cheap goods and a healthy stock market (and healthy retirement funds), and if done wrong, can undermine the middle class’s economic situation further.
It is not clear whether Trump will be driven by the GOP’s rich donor class, or Bannon’s alt-right ideology, or his own half-baked near-sighted populism when making his trade and immigration policies.
The Democratic Party could critique his economic message more on these issues, talk in more detail of cheap goods and cheap labor supply chains crisscrossing across national boundaries that sustain (and also undermine) middle class economic well-being. Replying to Trump's simplistic rhetoric with social justice arguments or with proforma leftist anti-trade rhetoric is just not good enough to get through to the middle class voter.
The same goes with Social Security, Medicare, other federal assistance programs, Obamacare, Wall Street regulation, student loans, role of government to ensure fair play for business growth and corporate responsibility. The middle class’s economic well-being is closely tied to all of these, though the GOP will not admit it. To get the middle class voter’s attention, the Democratic Party needs to make more forceful economic arguments even while making their social justice, equality and pluralism arguments.
The middle class voter wants a warm fuzzy feeling and doesn't care that for many years he has voted against his own economic interests. Trump has promised him that warm fuzzy feeling, good jobs, healthcare, social security, strong military, good infrastructure and all with low taxes . Meanwhile he appoints billionaire plutocrats to his Cabinet and has an unknown array of business interests of his own. Currently the Democratic Party is not authoritatively calling his bluff.