The hourlong debate in Troy followed the pattern of the first debate last week in New York City, with some sharp policy disagreements punctuated by pointed personal exchanges.
Polls show Gillibrand, a former congresswoman appointed last year to replace Secretary of State Hillary Rodham Clinton, with a wide lead over DioGuardi. DioGuardi, a former congressman from Westchester County, quickly tried to cast Gillibrand as someone who changed her views on issues when she went to the Senate.
"When I get to Washington, I will rock the boat, something that she has not done," DioGuardi said. "The closest she has gotten to rocking the boat is flip-flopping on every issue of importance to New Yorkers."
Gillibrand fired back often, saying DioGuardi praised the idea of privatizing Social Security in a book he wrote in 1992.
DioGuardi said privatization could not be considered an option today.
On policy, Gillibrand said President Barack Obama should not have told the Justice Department to appeal a decision by a federal judge that invalidated the "don't ask, don't tell" policy preventing gays from serving openly in the military. DioGuardi favored waiting for a consensus from military leaders.
Gillibrand called the health care overhaul "commonsense reforms" that will bring down costs. DioGuardi countered that the bill did nothing to reduce the cost of health care.
DioGuardi did not like the process that allowed Gillibrand to take Clinton's seat without a special election. Gillibrand had no problem with the process.
DioGuardi thought the tea party was good for America; Gillibrand did not. Gillibrand said she would, if invited, attend an opening ceremony of an Islamic community center and mosque near the World Trade Center site; DioGuardi would not.
They both agreed that rent is too high, a point hammered home in a debate earlier this week by Rent is Too Damn High party gubernatorial candidate Jimmy McMillan.
DioGuardi, a certified public accountant, asserted that he knew nothing about a fundraising scandal that preceded him losing a re-election bid to his House seat in 1988. He said when he heard allegations that a local businessman serving on his finance committee was funneling illegal contributions, he asked federal officials to investigate. And he dismissed the notion that he did anything wrong in a tax dispute over 1978 earnings in which he eventually paid $20,468 in back taxes.
"These are just serious questions that voters have a right to know about," Gillibrand said.
"My life's an open book," DioGuardi responded.
DioGuardi bought up Gillibrand's past work as a lawyer for the tobacco industry and as a counsel for the U.S. Department of Housing and Urban Development. He claimed Gillibrand had promoted subprime mortgages and began airing a cable ad Thursday making the same claims.
Gillibrand said she was young associate at a large firm when she worked for tobacco interests and adamantly denied promoting subprime mortgages while at HUD.
"Mr. DioGuardi, your allegations are entirely absurd and really quite ludicrous," she said.
They both cast themselves as independent politicians. DioGuardi, a conservative, said even President Ronald Reagan could not always count on his vote when he was in Congress in the 1980s.
Gillibrand disputed the idea that she too often follows the lead of Sen. Charles Schumer, saying she didn't always agree with him but that the two Democrats see many issues similarly.
"I'm glad that Sen. Schumer agrees with me so often," she said.