Tuesday's primary elections confirmed that anti-incumbent fever is sweeping the nation, with establishment candidates from both the Democratic and Republican parties suffering crushing defeats. Democrats in Pennsylvania denied 80-year old Sen. Arlen Specter — a longtime Republican who switched parties last year — a chance to run for a sixth term, while their counterparts in Arkansas forced incumbant Sen. Blanche Lincoln into a June 8 run-off with an unexpectedly close vote. In Kentucky, Tea Party favorite Rand Paul, son of the libertarian Rep. Ron Paul, humbled the Republican establishment's preferred candidate. But a Democratic victory in a special election for a House seat in a socially conservative Pennsylvania district suggested there may be limits to the public's appetite for change. Here's a rundown of the big races, and how the pundits are interpreting the results:

1. Sen. Specter (D-PA) loses to Rep. Sestak (D-PA)

Switching parties didn't work: "Specter learned that changing parties isn't a solution for a centrist in a world where the media and primary voters are highly partisan and ideological." Will Bunch, Philadelphia Daily News

Incumbents are dropping like flies: "Elected five times to the Senate as a Republican, Specter had the support of President Obama and the political leadership of his state, but he ran into rank-and-file resistance inside his new party and became the third member of Congress to lose his own party's support in the past two weeks." Dan Balz and Chris Cillizza, The Washington Post

Specter's loss was "no huge shock": "Something can be dramatic without being especially surprising. Joe Sestak is a mainline, lunchpail Democrat who defeated a very unpopular Republican-turned-Democrat who ran an awful campaign and who Pennsylvania Democrats weren't used to punching their ticket for." Nate Silver, FiveThirtyEight

Specter's loss is sweet, but not helpful for the GOP: "It’s a pyrrhic victory, arguably, since Sestak actually polls slightly better against (GOP candidate Pat) Toomey than Specter does and doesn’t have to shoulder the burden of incumbency in this very anti-incumbent year." Allahpundit, Hot Air

2. Sen. Blanche Lincoln (D-AR) forced into a run-off

Democrats aren't happy with moderates:
"It is never a good sign for an incumbent to be in a runoff; it signals that a majority of the voters have already decided not to go with the status quo. (Lt. Gov. Bill) Halter’s strong showing against Lincoln also showed the strength of the left wing of the Democratic Party, angered that 'Blue Dog' Democrats were not there for liberal and pro-labor legislation." Hastings Wyman, Southern Political Report

This was a vote against Obamacare: "Lincoln, like many blue dogs, has found herself feeling the wrath from both sides of the aisle. Conservatives won't support her again after failing to stop Obamacare in its infancy and the left will not support her for now trying to act like a conservative." Clifton B, Another Black Conservative

Lincoln still has a chance: "It wasn't a great night for Lincoln, but it wasn't devastating. She lived to run another day." But if she loses the run-off, "it will certainly send a chill down the spine of other centrist Democrats fearful that a loss to a Democrat, not a Republican, could end their congressional careers." Mark Preston, CNN

Sorry, Lincoln's seat belongs to the GOP now: "Numerically, it would appear that Lincoln can hold on in the June 8 run-off. But without a substantial change in her political fortunes, she’s got no hope come November (against GOP nominee Rep. John Boozman). On a national level, it would appear that Democrats are just going to need to let this one go." Michael Roston, True/Slant

3. Democrat Mark Critz wins in PA's 12th District

So much for the Republican revolution:
"This was the race that was going to show how (GOP House leader) John Boehner was on his way to becoming Speaker. Oops. Critz isn't exactly a progressive. But, given how cocky the Republicans have been about their electoral prospects, this is a sweet win." Joe Sudbay, America Blog

This wasn't exactly an endorsement of Democrats: "(Republican candidate) Tim Burns' task was complicated by the fact that he was running against a pro-life, pro-gun Democrat who ran against the health care bill and the cap-and-trade legislation." Jim Geraghty, National Review

This doesn't mean much — Critz benefited from turnout for Specter's race: "The Democrats were more motivated in this race. This ain't the end of a trend. It's just another special election, in a Democratic district, and on a big Democratic primary day. And a Democrat won. Disappointing. But not paradigm-smashing." Kathryn Jean Lopez, National Review

Maybe Democrats will keep control of Congress, after all: "Given the resources the GOP poured into the effort to capture the seat and the decisiveness of the defeat — as it turned out, it wasn’t really that close — the outcome casts serious doubt on the idea that the Democratic House majority is in jeopardy." Jonathan Martin and Charles Mahtesian, Politico

4. Tea Partier Rand Paul's  wins in Kentucky
Read The Week's roundup of opinion on Paul's GOP primary victory here.