Stamford - Democrat Richard Blumenthal said he would urge President Barack Obama to "hold firm and fight hard" in his effort to extend Bush-era tax cuts for the middle class and businesses but allow the tax cuts extended to the wealthy to expire at the end of the year.

Obama was in Stamford Thursday for a fundraiser to benefit Blumenthal's campaign against Republican Linda McMahon, and the two also appeared together at a Democratic National Committee fundraiser in Greenwich later in the evening.

"Some Republicans, including my opponent, are seeking to block those middle-class tax cuts unless and until the wealthiest families receive tax cuts as well," Blumenthal said in a press conference at his campaign office. "That's wrong. Middle-class families need and deserve tax cuts now."

Blumenthal supports the compromise being floated by the Obama administration and many congressional Democrats: extending the existing tax rates for individuals making less than $200,000 per year and families making less than $250,000, as well as the Bush administration cuts aimed at businesses, including cuts targeted to business investment and child care.

All the cuts, including those for taxpayers earning more than $200,000, are scheduled to expire at the end of the year, but both parties have moved to preserve at least the bulk of the cuts to avoid prolonging or deepening the nation's current economic stagnation.

McMahon told reporters Tuesday that she supported the harder line staked out by some Republicans in Congress, insisting that all the cuts must be extended, including those for wealthy taxpayers.

Responding to the president's visit, the McMahon campaign released a Republican-produced video showing President John F. Kennedy in 1962 arguing in favor of stimulative tax cuts, and e-mailed reporters with figures, including a report by the conservative Heritage Foundation, that show wealthy taxpayers in Connecticut would pay an aggregate of $1.8 billion if the marginal rates return to pre-Bush levels.

"Only four states in the union will be hit harder than Connecticut by Blumenthal's proposed tax hikes," the McMahon campaign message read.

Blumenthal's press conference was wide-ranging, and in it the candidate also addressed the groundswell of concern among many Connecticut Democrats that he has not responded forcefully enough to McMahon's allegations about his policy positions and character.

Blumenthal said he was facing a "$50 million negative attack machine," adding that some of McMahon's negative mailings and commercials about him were "false." He specifically cited a mailing that blames him for having supported previous cap-and-trade proposals to combat global warming but asserts he would support an "energy tax." That is not accurate, Blumenthal said, adding, "Cap and trade is dead."

Congress must act to develop a new energy policy that rewards states that use cleaner energy sources, he said.

Blumenthal also denounced McMahon's allegations that he would support "Medicare cuts" by virtue of his support for most provisions of the Obama administration's health care reform law. In fact, Blumenthal said, he has pledged not to support any reduction in Medicare services; the "cuts" criticized by McMahon are savings in the health care bill created by eliminating subsidies for insurers in the Medicare Advantage program, not reductions in benefits, Blumenthal said.

The benefit at the Stamford Marriott was not cheap: $1,000 for general admission and $12,400 for a photograph with President Obama. (The Blumenthal campaign will keep $2,400 of the higher rate, with the remainder going to the DNC.) Organizers were expecting more than 300 guests, a Blumenthal spokeswoman said.