Conservative governors are signing on to provisions of what they once derisively dismissed as Obamacare. Prominent Senate Republicans are taking positions on immigration that would have gotten the party's presidential candidates hooted off the debate stage during last year's primaries.
Same-sex marriage has gone from being a reliable motivator for the conservative base to gaining broad acceptance.
Republican lawmakers are so fearful of social issues, in fact, that House leaders ignored intense objections from conservatives last week and allowed the passage of Democratic legislation on domestic and sexual violence against women.
All of which helps explain why Speaker John A. Boehner and Congressional Republicans have been so intent on facing down President Obama in their budget dispute. Aware that conservatives could never accept a second round of tax increases this year — and that compromising with Mr. Obama on his terms would lead to party divisions far deeper than those that have emerged so far — Republicans judged that the better course was to take on the economic and political risks associated with the automatic spending cuts that took effect on Friday.
"I'm going to say it one more time," Mr. Boehner said Sunday on "Meet the Press" on NBC. "The president got his tax hikes on January the First. The issue here is spending. Spending is out of control."
Four months after Mr. Obama won a second term, the only issue that truly unites Republicans is a commitment to shrinking the federal government through spending cuts, low taxes and less regulation. To have compromised again and agreed to further increase taxes or roll back spending cuts would have left Republicans deeply split and, many of them say, at risk of losing the core of the party's identity.
"If the voters can't rely on us to stand up to the runaway train of entitlements and deficits and federal debt, what can they count on us for?" said David Kochel, a Republican consultant in Iowa. "We're going to have disagreements on other issues. This is one we have to agree on."
One of the most striking characteristics about the political climate in the months since Mr. Obama's re-election is that on issue after issue, it is no longer entirely clear what it means to be a Republican. The party is more divided than ever on domestic policy, and a debate is breaking out over how best to invigorate the conservative movement.
In that sense, the budget showdown is not just about cutting $85 billion out of government spending over the next seven months. It is, to many conservatives, about showing that Republicans still have the will, the leadership and the public support to use this moment to halt, or at least slow, an ideological pendulum swing from the right, where the nation seemed to be heading after the 2010 midterm elections, to the left, after the 2012 campaign.