Former Vermont governor Howard Dean (D) will headline a Pennsylvania fundraiser for Rep. Joe Hoeffel later this month, the one-time presidential frontrunner’s first such event for a Democratic Senate candidate this cycle.

The May 23 fundraiser will be held at a private home in suburban Philadelphia.

Hoeffel is trying to unseat 24-year incumbent Sen. Arlen Specter (R), who narrowly escaped a primary challenge from Rep. Pat Toomey (R) last month.

“We understand that Joe Hoeffel is the first Senate candidate in the country that is getting this kind of fundraising help from Governor Dean,” said Hoeffel campaign consultant David Stone. “We’re excited about it.”

Stone said the campaign expects other national party figures to become involved in the race.

“It signals that national Democrats are focusing on this race and it’s a winnable race,” he said.

Hoeffel had $800,000 in the bank as of March 31. Specter, meanwhile, ended the primary with about $2 million in cash on hand after spending upwards of $12 million to beat back Toomey.

“Governor Dean is thrilled to go campaign on behalf of Joe Hoeffel,” said Dean spokesman Walker Waugh. “He thinks that the ideas and the values that Joe Hoeffel has is directly in line with Pennsylvania and Pennsylvanians.”

Waugh added: “We think it’s a winnable race.”

While Dean’s schedule of events on behalf of Congressional candidates is still being worked out, Waugh said the former governor expects to make appearances “in battleground states and on behalf of candidates that he thinks best represent the ideas” that Dean campaigned on.

National Republican Senatorial Committee spokesman Dan Allen was unimpressed with news of the Dean event — and the Democrats’ handicapping of the race.

“So they’re sending Howard Dean, who apparently had a huge organization and a huge money lead and squandered it all and failed to win any state except his own, Vermont, in the Democratic primary?” Allen asked. “Arlen Specter is well positioned to win again in the fall, and the Democrats are going to have a hard time convincing people otherwise. The only thing harder than that is going to be beating Arlen Specter.”

Dean never regained his footing after finishing a disappointing third in the Iowa caucuses, despite raising more than $50 million for his presidential campaign.

Since ending his White House bid in February, Dean has formed a new political organization to aid not only the Democratic effort to win the White House, but also to help his party regain control of both houses of Congress.

He has sent e-mail fundraising appeals on behalf of two House Democrats so far, Reps. Leonard Boswell (Iowa) and Jesse Jackson Jr. (Ill.). In late December, he raised $52,000 for Boswell in just 24 hours.