Republicans will head to the polls Tuesday in Virginia’s primary election to choose a candidate to face former governor Timothy M. Kaine (D) in the state’s marquee race for U.S. Senate in November.

In Northern Virginia, Democrats will decide whether Rep. James P. Moran deserves to prevail over a primary challenger while Republicans will pick among two candidates running to take on Rep. Gerald E. Connolly (D). On the local front, Alexandria Democrats will winnow down a long list of City Council hopefuls.

The main event in the primary is the Republican Senate contest, where three candidates are challenging front-runner George Allen, a former governor and senator who far surpasses them in fundraising and name recognition. The contentious and expensive race to succeed Sen. James Webb (D), who is retiring, is expected to help determine the Senate’s balance of power next year.

Allen’s rivals — Chesapeake minister E.W. Jackson, Del. Robert G. Marshall (Prince William) and tea party activist Jamie Radtke — have spent months running to his right and criticizing him for failing to challenge the status quo.

But Allen has set his sights on Kaine, focusing on his terms as governor and Democratic National Committee chairman for President Obama.

In this 2011 file photo, former Virginia governors Tim Kaine, left, and George Allen, also a former senator, greet each other in Richmond. (Steve Helber/AP)

Allen has been careful to avoid gaffes like those that contributed to his reelection loss in 2006, mostly speaking generally about the need for new energy sources, smaller government and less regulation. He has not answered specific questions on pay equity legislation, a plan by Rep. Paul Ryan (R-Wis.) to overhaul entitlements and whether he would support requiring women to undergo ultrasounds before abortions.

‘Smart money’ on Allen

Stephen Farnsworth, a political science professor at the University of Mary Washington, said it is rare for someone with the national recognition of Allen, who has been in Virginia politics for more than two decades, to be defeated in a primary.

“To say the smart money is on George Allen is one of the biggest understatements of the week,’’ he said.

A Washington Post poll last month showed Allen getting 62 percent of the vote among likely GOP primary voters. Marshall was next with 12 percent, ahead of Radtke at 5 percent and Jackson at 3 percent.

The four Republican candidates agree on many issues, all backing the Defense of Marriage Act, a repeal of the federal health care law, and smart spending on the military. They took part in three debates, but all took place on days when Virginians were unlikely to pay attention — over Memorial Day weekend, for instance. Only one was televised.

Bob Holsworth, a former professor who moderated the final debate, said it has been difficult for the others to call attention to themselves, because there is more than one opponent.

“There’s no requirement that [Allen] has to engage them,’' Holsworth said. “It’s very difficult for any single candidate to make a very sharp distinction with Allen.’’

Jackson, who has never held office, drew praise for his oratory, stressing the need for increased freedom and reduced spending. Marshall, one of the most conservative members of the House of Delegates, focused on his record passing a bill that paved the way for Virginia’s lawsuit against the federal government on health care and another that allowed voters to decide that marriage should be between a man and a woman.

But Radtke has been the most aggressive against Allen, in recent days launching radio ads that attacked him as a big spender.

Allen received the backing of the American Conservative Union and the National Rifle Association, providing him with support on the right. He launched a two-week tour of Virginia, during which he appeared with most of the state’s top Republicans, including Gov. Robert F. McDonnell and House Majority Leader Eric Cantor.

House races

Among the U.S. House races, the most competitive primary is unfolding in Connolly’s Fairfax-based 11th District, where retired Army Col. Chris Perkins and traffic engineer Ken Vaughn are battling for the Republican nod.

Perkins has emphasized his military background, pledging to bring integrity and leadership skills to Congress, while Vaughn has focused heavily on his plans to balance the budget and reduce the federal debt. Perkins has the backing of Tom Davis, who represented the district from 1995 to 2008. Vaughn has the support of some Northern Virginia tea party activists.

Neither man has raised much money, and the well-funded Connolly will begin the general election with a leg up on whichever Republican wins Tuesday, especially since his district was redrawn to be somewhat safer for the Democrat.

Next door in the 8th District, Moran faces a challenge for the Democratic nomination from Bruce B. Shuttleworth, a Navy veteran and business consultant who has focused his campaign on the idea that the incumbent is too business-friendly and too ethically challenged to keep his post, a notion that Moran’s campaign strongly disputes.

Shuttleworth is little known in the district — which includes Alexandria, Arlington County, Falls Church and a portion of Fairfax County — and did not raise enough cash to run a media campaign to boost his name recognition. Moran has fended off better-funded challengers in the past and is the heavy favorite again Tuesday. Retired Army Col. Patrick Murray is unopposed for the Republican nod.

Democrats have already settled on candidates in two other districts, with lawyer Kristin Cabral challenging Rep. Frank R. Wolf (R) and Air Force Reserve lawyer Adam Cook set to face Rep. Rob Wittman (R).

Beyond Northern Virginia, Cantor and fellow Republicans J. Randy Forbes and Bob Goodlatte face primary challenges. Cantor faces teacher Floyd Bayne, Forbes is being challenged by business consultant Bonnie Girard, and Goodlatte goes up against conservative activist Karen Kwiatkowski. All three incumbents are expected to win easily.

In Alexandria, voters in the Democratic primary will choose from among 14 candidates for six City Council seats. The crowded field includes a mix of political veterans and electoral newcomers, and much of the primary debate has focused on proposed development along the city’s waterfront and in the Beauregard area.