GOP candidate Del. Bob Marshall, second from right, talks during the first of three debates, Saturday, April 28, 2012, in Roanoake, Va. Other GOP candidates participating in the debate are, from left, former Virginia senator George Allen, Chesapeake minister E.W. Jackson, and tea party leader Jamie Radtke. The winner of the primary will face former Gov. Tim Kaine in November. (Stephanie Klein-Davis/AP)

George Allen’s three foes for the Republican U.S. Senate nod sought to gang up on the front-runner at their first debate Saturday, while Allen focused on two men who weren’t in the room — Timothy M. Kaine and President Obama.

Virginia is a key battleground this year as Obama seeks to win the state for a second consecutive election and the marquee race to succeed retiring Sen. James Webb (D) has become one of a handful of contests that could decide control of the Senate.

Former governor Kaine faces no opposition for the Democratic Senate nomination, but Allen must get past his opponents in the June 12 Republican primary — Bishop E.W. Jackson, Del. Robert G. Marshall (Prince William) and former Virginia Tea Party Patriots head Jamie Radtke.

All three reminded the audience that Allen, a former governor, is also a former senator with a long record on spending they believe makes him the wrong man to take on Kaine in November.

“I have never voted for deficit spending,” Marshall said. “I can stand on my record. I do not have to run from it.”

Radtke criticized Allen for supporting earmarks in the Senate and not fighting hard enough to pass a balanced-budget amendment. She admonished Republicans who she said were insufficiently supportive of Rep. Paul Ryan’s (R-Wis.) budget proposals.

“If we do not deal with spending, nothing else matters,” Radtke said.

She attacked “career politicians of both parties,” arguing that Republicans “need a clear contrast” between their pick and Kaine.

Allen argued that the fiscal climate was different during his Senate term (which ended when he lost to Webb in 2006) and suggested that much of the spending he supported was aimed at bolstering national security after the Sept. 11, 2001, attacks.

Referring to increases in the debt ceiling he and other Republican backed, Allen said, “Those were those days, and now is different.”

Given the current size of the deficit, he said, “I can’t see [supporting] any increases in debt limits unless there are concrete, ironclad spending restraints.”

Allen used his time during the hour-long debate to criticize “Tim Kaine and all these folks who have supported all this increase in spending and reckless debt and Obamacare and this stimulus spending that did not create the jobs that were promised.”

Allen contrasted his record with that of the Kaine on college tuition costs and energy, among other issues.

The Republicans candidates agreed on many topics. They said they would have opposed the Supreme Court nominations of Justices Elena Kagan and Sonia Sotomayor. All said they back the Defense of Marriage Act and believe it is constitutional. (The Obama administration has declined to defend the law).

All four also said they would back the Republican nominee for president, but Jackson, Marshall and Radtke declined to offer their support for former Massachusetts governor Mitt Romney until he officially secures the party nod.

Allen said that “it looks like it’s going to be Romney” and that he would work well with Romney if both men win in November.

After the debate, Allen said, “I just talked about what I wanted to talk about.” He said he preferred to “focus on what I’m for” rather than criticizing his opponents.

But Radtke said the debate showed that “it’s very dangerous for [Allen] to engage, because then he has to defend his record.”

Meanwhile, Kaine’s campaign said in a statement that the debate demonstrated voters would have “a clear choice in November” between the Democrat and the GOP nominee. The approach Republican “candidates advocate would devastate federal investments in education, defense, and infrastructure that bolster and grow Virginia’s economy,” the statement said.

While several surveys have shown Kaine and Allen to be neck and neck, no recent polls have been taken of the primary contest. However, Allen enjoys stratospheric statewide name identification that his opponents don’t. He also has a massive fundraising advantage: Allen had $2.7 million in the bank as of March 31, while Radtke was second with just $80,000.

Roughly 500 people attended the debate at the Sheraton Roanoke, and it’s not clear how many other Virginians will end up seeing the session. It was streamed live on the Web site of a Roanoke television station, and each campaign is to receive a copy they can post on their sites.

The GOP contenders will face each other twice more before the primary — on May 11 in Virginia Beach and May 25 in Falls Church.