Each political party has a vulnerability: Principle
Republicans have the abortion issue.
Democrats care about racial and gender prejudice.
In both cases, it is a matter of principle.
Some issues in politics come down to deeply held moral values. Other issues can reach an accommodation through compromise. Does anyone think that a marginal tax rate on earned income of 37% is moral and just, but one of 38% is the work of the devil? Lobbyists care, some big donors care, and in the inside-baseball of D.C. partisan war, elections may be won or lost on whether a PAC gives or withholds money to a politician who "holds the line" at 37%. But the public doesn't care. Those issues are resolved by politics.
Some are not. Primary election voters of each party have issues that cannot be compromised because they are matters of principle. Compromise would infuriate some of one's longtime supporters. It would bring a primary election opponent or a third party spoiler in a general election. The abortion issue is this kind of issue for Republicans. Since the Dobbs decision, GOP legislators aren't choosing to tiptoe toward some politically advantageous compromise where the issue meets an uneasy middle ground. They are racing to fulfill the wishes of abortion opponents, and in red states are successful in doing so. Democrats use the issue to characterize Republicans as extreme.
The Democratic Party is a coalition of interest groups that revolve around support for the underdog. They oppose prejudice against minority races, religions, genders, and gender preference. Climate activists defend the vulnerable climate, considering it to be bullied by the dominant culture of fossil fuels and industrial polluters. Support for these issues a kind of secular religion, based on their version of principle and science. Republicans have found words in the Bible to defend their positions.
Democrats have a drag on their support that is as profound as the abortion drag on Republicans. Joe Biden masked that problem for Democrats. He is as well positioned as any nationally-known Democrat to make a bridge to White working class Americans. Biden was "Scranton Joe," an Irish Catholic union-supporting old-school Democrat. But even Biden is not persuading White working class Americans. White men voted 56-39 for Trump, and non-college White men voted 66-32 for Trump. Rural White non-college voters voted 75-24 for Trump. Republicans succeeded in presenting themselves as the party of White Christian Americans. Accelerated by the election of Obama, they understand themselves to be under siege. They understand themselves to be outmatched by powerful, educated elite snobs from above and outnumbered by growing numbers of ambitious minorities striving for preferential status. Politically engaged Democrats do, indeed, consider racial and religious prejudice "deplorable," to use Hillary's word. They consider misogyny deplorable. They consider prejudice against homosexuals deplorable. Democrats cannot compromise on racism and other prejudices. Republicans call Democratic policy extreme.
A Republican may emerge who attempts a new policy on abortion, presenting a new orthodoxy. I don't see one yet. It may not be possible until Republicans lose landslide elections. A Democrat with standing and credibility to change Democratic orthodoxy will likely need to be a person in a persecuted group. At this point no one is challenging either Biden or Democratic orthodoxy. I don't expect Democrats to change anytime soon, either.