Senate primaries for both parties today in Colorado represent the next big test of the strength of the anti-establishment mood of the electorate this cycle.

Although the Democratic contest represents the first time appointed Sen. Michael Bennet’s name will appear on a ballot, former state Speaker Andrew Romanoff (D) has found room to run as the outsider by tying Bennet to Washington, D.C., and Wall Street insiders.

Romanoff, who has eschewed political action committee contributions during the campaign, has been outspent by more than $4 million by Bennet. But he’s spent much of the race criticizing Bennet for taking more than $1 million in campaign contributions from special interest groups and being the choice of the party establishment.

The strategy has proved successful, if belatedly so. After Bennet led Romanoff for more than 10 months, late polling showed the race is a dead heat. A Denver Post poll from late last month showed Romanoff ahead by 3 points. Bennet’s camp claimed a 4-point lead in a tracking poll last week. A public poll from the weekend showed Bennet up by 6 points.

Surveys from the previous two weeks are noteworthy in this contest because relatively few Colorado voters will actually head to the polls today. Forty-six of Colorado’s 64 counties are holding only mail-in elections this year. Ballots began to be mailed out to voters July 19, and as of late last week about a quarter-million ballots had been returned for the Democratic primary.

Bennet strategists are hoping that number climbs well above 300,000 by Wednesday night because Romanoff, who is more familiar with hard-core party activists, is expected to perform better if turnout in the primary is relatively light.

The mostly mail-in primary also means that late-breaking developments will likely have less of an effect than they would under the more standard Election Day format.

On Friday, the New York Times published a story that was critical of Bennet for a financial deal he helped put together during his time as head of the Denver Public Schools.

“I heard from a lot of voters over the weekend who said, ‘Gosh I wish I had this information before they voted,'” Romanoff said Monday.

Regardless of who wins today — and insiders on both sides expect the contest to be very close — Democrats will be looking at another tough contest in the general election.

Romanoff’s one high-profile endorser, former President Bill Clinton, released a robocall for him Monday in which he said Romanoff has the best chance to hold the seat in November.

The Republican Senate primary pits former Lt. Gov. Jane Norton against Weld County District Attorney Ken Buck. After nearly bowing out of the race last fall, Buck saw his grass-roots campaign steadily gain ground over the spring and summer as tea party groups began to see Norton as the choice of the party establishment.

But after Buck appeared to take a commanding lead in polling in June, the Norton campaign seemed to find its stride in July. Norton used her $1.6 million financial advantage to blast Buck for a series of gaffes, including one in which he appeared to slam the very tea party supporters who helped his campaign catch fire.

Some Democrats are privately hoping that Buck can hold off Norton, as they believe he’ll be easier to paint as a right-wing extremist in the November contest.

Several House primaries will also take place in Colorado, although not in the 4th district, which is the most competitive in the state. In that contest, state Rep. Cory Gardner has a free pass to what will be a closely watched general election against freshman Rep. Betsy Markey (D). Republicans are hoping that the 3rd and 7th districts will also be competitive this cycle. Both those contests feature competitive GOP primaries.

Here is a rundown of the other races worth watching today:

Connecticut

While Nutmeg State voters will decide a competitive gubernatorial primary on the Democratic side, Republicans will resolve an increasingly bitter feud among three GOP Senate hopefuls.

The assumption on both sides is that former World Wrestling Entertainment CEO Linda McMahon will win the contest handily, setting up a matchup against state Attorney General Richard Blumenthal in November.

The timing of a Quinnipiac University poll released Monday morning — less than 24 hours before polls open — surprised some campaign staffers but offered confidence to a McMahon campaign under constant attack from within her party. The image of McMahon repeatedly kicking a man between the legs has been airing on television across the state for more than a week, courtesy of Peter Schiff, one of McMahon’s opponents.

“Peter Schiff has proven he is just another politician who will say anything to get elected, even if it means distorting Linda’s positions and lying to voters about where she stands on important issues,” McMahon spokesman Ed Patru said in a statement. “We are confident that Connecticut voters on Tuesday will back Linda, the only fiscally conservative outsider with a record of job creation who can beat Dick Blumenthal.”

The Quinnipiac Poll showed McMahon with a 50 percent to 28 percent lead over former Rep. Rob Simmons, who suspended his campaign in late spring only to resurrect his bid in recent weeks. Schiff had 15 percent of the vote in the survey of 664 likely GOP voters taken Tuesday to Sunday.

“In the Republican Senate contest, it looks like Rob Simmons would need more than a surprise; he would need a miracle to catch Linda McMahon,” Quinnipiac Poll Director Douglas Schwartz said. “But in politics, miracles do happen.”

While the McMahon campaign acknowledged that a low turnout could produce a far closer contest, the candidate has run a strong race to date, spending more than $21 million from her own pocket.

The Senate race is not the only Congressional primary in Connecticut today.

The 4th and 5th districts have the most potential to be competitive in November, although national Republicans are not hopeful that the winner of either race could flip the Democratic-held seats.

Their best hope may be the 4th district, where Republican challenger Dan Debicella won the state party endorsement and reported more than $492,000 on hand as of June 30 for the general election battle against Rep. Jim Himes, who reported nearly $1.89 million in his campaign coffers.

“Debicella should come out of the primary with a strong win and will pick up a key endorsement in the next couple weeks, which will give him a lot of momentum,” said Greg Blair, a spokesman for the National Republican Campaign Committee.

That endorsement is expected to come from former Rep. Christopher Shays (R), who was defeated by Himes in 2008.

Georgia

Peach State voters head back to the polls for several runoffs. In the 9th district, Rep. Tom Graves (R), who won a special election earlier this summer, will again face former state Sen. Lee Hawkins (R), who came in second in the June contest. Graves is having an easier time now that he’s the incumbent. He came just shy of wrapping up the nomination last month and is widely expected to finish the job today.

Republicans will also pick their nominee in the conservative 7th district open seat, where Jody Hice and Rob Woodall are vying to succeed retiring Rep. John Linder (R). Woodall is Linder’s former chief of staff and has the backing of his old boss. The winner of the runoff is all but assured of winning this fall.