Democrat Tim Kaine said he was "open to a proposal" that would require even the poorest Americans to pay income taxes, prompting attacks from his Republican rival in Virginia's U.S. Senate race, George Allen.

Kaine made the statement Thursday during his first televised debate with Allen after the two candidates were asked if they agreed with Republican presidential nominee Mitt Romney's claim that 47 percent of Americans are dependent on government and don't pay taxes.

Kaine said everyone in Virginia already pays some taxes. But when pressed about whether those now exempt from taxes, including low-income families, should also pay, Kaine said, "I would be open to a proposal that would have some minimum tax level for everyone."

(View a photo gallery from the debate)

Allen didn't react to Kaine's statement during the debate. But when reporters asked Allen about it afterward, he admonished Kaine for wanting to raise taxes on financially strapped Americans. Within hours, the Allen campaign was circulating a video of Kaine's remarks.

"I don't think everyone in this country ought to be paying federal income taxes," Allen told reporters. "Families are struggling right now."

(Watch highlights from the debate above, and post-debate interviews with the candidates below)

Kaine's comment provided additional ammunition to Allen, who has already criticized the Democrat for proposing a tax increase as governor of Virginia and for wanting to end Bush-era tax breaks for those earning more than $500,000 a year.

Kaine later said that as a senator he would be open to all options to balance the federal budget, and he chastised Allen for insisting that the deficit be reduced solely through spending cuts.

"It shouldn't be news that somebody who wants to go into the Senate is willing to start from the position of openness and dialogue," Kaine said.

The televised debate was the first opportunity many voters had to watch Kaine and Allen spar, and it came just as three new polls for the first time show Kaine opening a sizeable lead in what had long been a deadlocked race. Kaine and Allen, both former governors, are running to replace retiring Sen. Jim Webb, D-Va.

Though he was ultimately forced to play defense on the tax issues, Kaine was on the attack during a debate that focused sharply on the economy.

Kaine attacked Allen's record as a U.S. senator, accusing him of supporting wasteful spending. And he insisted that Allen address social issues he's been trying to avoid, like same-sex marriage and abortion, saying they were also economic issues.

And the Democratic hopeful moved to capitalize on the bigotry charges Allen has been battling since he called an Indian-American man "Macaca" in his 2006 campaign. Kaine said the kind of divisive rhetoric Allen uses was already preventing Congress from doing its job.

Allen and Kaine both distanced themselves from their parties' presidential nominees as they battled for moderate and independent voters. Kaine said President Obama likely made mistakes in handling unrest in the Middle East. Allen dismissed Romney's complaint about government-dependent Americans believing they're victims.

"I have my own point of view," Allen said.

Kaine and Allen will square off twice more in October before the Nov. 6 election.