The candidates shake hands before the Fairfax County Chamber of Commerce hosts Virginia's U.S. Senate debate between Democratic U.S. Sen. Mark Warner, right, and Republican challenger Ed Gillespie on Oct. 7 in McLean. (Bill O'leary/AP)

Virginia’s candidates for U.S. Senate zigzagged across the commonwealth Monday to make one last push in their tightening contest, while contenders in the state’s hardest-fought House race focused on getting out the vote in a Northern Virginia swing district.

Republican Ed Gillespie declared that momentum was on his side in his underdog bid to unseat Sen. Mark R. Warner (D), making note at a morning rally of narrowing polls and the energy of a volunteer squad he dubbed his “G-Force.”

“I honestly believe we overtook him this weekend and that tomorrow we’re going to surprise a lot of experts in Washington, D.C., and have a big, big day,” Gillespie said at a Republican campaign office in the Richmond suburbs. Having begun the day in Newport News, Gillespie later hopscotched to Roanoke, Staunton, Charlottesville, Harrisonburg and ended the day in Sterling with Ann Romney, wife of former presidential candidate Mitt Romney.

Warner, his voice more gravelly than usual, gave a spirited get-out-the-vote pitch to volunteers at his Richmond headquarters, his second stop in a day that also took him to Norfolk, Roanoke and Alexandria.

“I got two rallies left and not much voice,” he said. “So you need to be my voice, you need to be my footsteps, you need to be our foot soldiers.”

Later in the day, more than 150 people gathered in Old Town Alexandria, Warner’s home, for a final evening rally. Warner’s campaign team said he had been to at least 11 cities since Saturday.

In the 10th Congressional District race, Republican Barbara J. Comstock and Democrat John W. Foust were out canvassing neighborhoods, shopping malls and other spots for last-minute votes.

A planned Monday evening rally in Sterling for Foust and Warner was canceled, with both campaigns saying that they would focus on getting out the vote rather than pulling volunteers off the street hours before the polls opened.

As Comstock greeted voters inside a Haymarket shopping center with her sons, Peter and Dan, the Virginia state delegate from Fairfax County predicted she would win as part of a broader Republican sweep in Congress.

“The 10th District and the Northern Virginia, Shenandoah Valley region needs to have a voice in the majority,” Comstock said. Comstock also appeared with Gillespie and Romney at the end of the day.

Foust, a Fairfax supervisor from McLean, said his campaign has been calling voters and knocking on doors to encourage people to vote.

“Our ground game has been absolutely spectacular,” Foust said during a breather inside his Manassas campaign office, where he later delivered a pep talk to volunteers.

The elections will put Virginia’s new voter identification law to the test, and voter rights groups were gearing up to monitor polling places to see whether it makes it harder to vote.

Acceptable forms of identification include photo IDs issued by state or federal government, Virginia colleges or workplaces. Voters who arrive at the polls without proper identification will be allowed to vote by provisional ballot. But those votes will be counted only if voters show an existing photo ID, or apply for a new one, at their local voter registration office by noon Friday.

Polls will be open from 6 a.m. to 7 p.m.

Voting is expected to be light in a state where the top-of-the-ticket race has been relatively low-key and where turnout rarely cracks 50 percent in non-presidential years. (It has done so just once since 1995, in 2006, when a fierce battle for the U.S. Senate between Jim Webb and Republican George Allen drew nearly 53 percent of voters to the polls, according to the nonpartisan Virginia Public Access Project.)

The number of voters who requested absentee ballots — a good barometer of interest — was just under 132,000 this year, down sharply from the 476,000 who did so in 2012, the last presidential year, according to the Virginia Department of Elections.

The weather was not expected to deter voting, with clear skies and mild temperatures predicted.

The Senate race pits Warner, a former Democratic governor seeking his second term in the Senate, against Gillespie, a former White House adviser, lobbyist and Republican National Committee chairman making his first bid for elective office. Warner has long been Virginia’s most popular political figure. But Gillespie is challenging him in a year when President Obama’s low approval ratings have been a drag on Democrats nationally.

Gillespie began the race far behind in polls and fundraising. A survey early this year put Warner 30 points ahead. But a Christopher Newport University poll released Friday had Warner up by just seven points.

Speaking to a crowd of about 300 in Loudoun County, Romney said that in her husband’s presidential campaign, Gillespie was a “voice of reason” in difficult strategy sessions. “You can trust Ed,” she said. “He is a good man,” and, she added, he is going “to shock the country” by winning on Tuesday.

At Warner’s rally in Richmond, the senator emphasized his reputation for bipartisanship.

“Virginians at the end of the day know me and they know my record,” he said. “You’ve got a choice this election. You can send one more hardcore partisan or you can send somebody back who’s a bipartisan problem-solver, and I think people are ready for some problem-solving.”

Miles Parks, Antonio Olivo and Rachel Weiner contributed to this report.