The shifts reflect a fact of life for tea party supporters: Their preferred standard-bearers – Herman Cain, Minnesota Rep. Michele Bachmann, Texas Gov. Rick Perry – have toppled one by one. Even with Santorum’s victories this week, the Republican nominee could well be Romney, the moderate former governor of Massachusetts…

Resignation seems to be the overriding mood among tea party activists around the country. In the aftermath of the 2010 midterm elections, this headless coalition of citizen-warriors — enraged by what they saw as out-of-control federal spending and government overreach — was lionized for helping the GOP capture a majority in the House of Representatives and post impressive gains in the Senate and statehouses across the country.

Two years later, there’s mounting evidence that tea party influence is on the wane, particularly when it comes to the biggest race of all. The only options left now are Romney, who signed “Romneycare” – a close relative to the conservative bane of “Obamacare”; Newt Gingrich, a former speaker of the House who supported both an individual health care mandate and cap-and-trade legislation before running for president; Santorum, a former U.S. senator from Pennsylvania who secured millions of dollars in earmarks during his years in Congress; and Rep. Ron Paul, R-Texas, whose isolationist foreign policy scares off a fair number of conservatives.