In a year that has already delivered more than its share of political shocks, the question in advance of a slate of high-stakes elections Tuesday is simple: How many more will there be?
The answer will come on what is, so far, the biggest election day of the year, with competitive contests in Pennsylvania, Kentucky and Arkansas that have put the political establishment in both parties on edge.
Sen. Arlen Specter, D-Pa., could be the next incumbent to fall, but by late Tuesday, everyone from President Barack Obama to Senate Minority Leader Mitch McConnell, R-Ky., could feel the sting of voter anger that has shaped the election climate and that could produce a dramatic upheaval in Congress by November.
Everyone has a different definition of the anger: anti-incumbent; anti-Obama; anti-establishment; anti-Washington. But the expressions of displeasure are everywhere. Some voters believe Washington is spending too much and infringing on their rights. Others say Washington is not doing enough — to penalize bankers or to oversee the cleanup of the Gulf of Mexico.
Democratic pollster Peter Hart said the meaning from Tuesday's races is in grievances that have been building for months. "How many times do we need to tell the same story, which is that voters are looking for something that is not in Washington right now," he said.
The past seven months have been unsettling. Republicans picked up governorships of Virginia and New Jersey and, in a seismic shock, the Massachusetts Senate seat held by Edward Kennedy. Last weekend, Sen. Robert Bennett, R-Utah, was defeated at a party convention and a few days later Rep. Alan Mollohan, D-W.Va., lost his primary.
Whit Ayres, a Republican pollster, said the contests this week "will be another measure of the depth of anger at Washington and the current state of the country."
The marquee race is the Democratic Senate primary in Pennsylvania, where Specter, who switched parties in 2009, trails Rep. Joe Sestak. Elected five times as a Republican, Specter defected to the Democrats because he feared he might lose his bid for renomination in the Republican primary. Now, he could lose as a Democrat, even with the support of Obama and the Democratic establishment.
A second Democratic senator, Blanche Lincoln of Arkansas, is also fighting for survival against Lt. Gov. Bill Halter. Whoever wins the Democratic nominations in those states faces stiff competition in the fall for Senate seats.
Republicans have their own intraparty warfare to contend with Tuesday. Kentucky has become a laboratory for measuring the relative powers of the "tea party" movement vs. the GOP establishment in the race to succeed retiring Republican Sen. Jim Bunning. There, upstart Rand Paul is seeking the Senate nomination against Secretary of State Trey Grayson, who enjoys the support of McConnell, the state's pre-eminent Republican.
A fourth contest on Tuesday — a special House election in Pennsylvania to fill the vacancy created by the death of Democratic Rep. John Murtha — could provide clues to the prospects for Republicans to capture control of the House in November.