The White House drive to maintain Democratic control of Congress appears to be heating up, with President Barack Obama scheduled to attend three events later this month and Vice President Joseph Biden intensifying his presence on the money trail.

“We plan on using the president early and often,— said one Democratic strategist who spoke of the expected Obama Congressional campaign blitz. “We feel like he’s very popular with a strong base of support that is not likely to erode.—

Beloved by the Democratic base and a proven money magnet, Obama could be the key to Democrats’ retaining the House and keeping their sizable majority in the Senate. But it is not yet clear how many Democrats running in Republican-leaning states and districts will seek help from a man who increasingly antagonizes the Republican base.

Obama’s poll numbers plunged during the spring but have recently stabilized above a 50 percent approval rate, most polls agree. And many Democrats expect the economy and employment to pick up next year and help bolster the president’s ratings — and his effectiveness on the trail.

But many of the most critical races will be in red-state Senate contests and the dozens of Congressional districts won by Sen. John McCain (R-Ariz.) in the 2008 presidential election but held by Democratic Members. There, Obama may do little more than drop in to raise money with well-heeled local Democrats while eschewing rallies.

“Every campaign will take a poll and ask about the president and how popular he is,— said Steve Elmendorf, chief of staff for former House Minority Leader Richard Gephardt (D-Mo.) and now head of Elmendorf Strategies.

But Democrats with a heavy GOP presence in their districts may take a hit for inviting Obama in to raise money, even if he doesn’t get past the airport.

“It would be viewed as a sign of desperation,— one Republican official said.

But Elmendorf said it would be “a pretty high bar— not to invite a sitting president into the district. “The president is a net positive in most places,— he said.

Obama is expected by Democrats to spend substantial time in several Democratic-leaning states where Senate contests may be fierce. “Illinois, Delaware and New Hampshire are three states where I think you’ll see a lot of him,— the Democratic strategist said.

But Obama will also have plenty of incentive of his own to visit closely contested states that sit in the middle or lean toward the Republicans — but where his own re-election may be decided in 2012. Such states include Ohio, Missouri, Florida and North Carolina, Democratic sources said.

And he may work his way out from there.

“The president has proven appeal to a broad range of Americans,— another Democratic operative said.

Obama, who is said by advisers to loathe fundraising, has nevertheless shown he can drum up awesome sums of money for himself, and there are indications that he can do so for other candidates as well. Two events held Sept. 15 in Philadelphia for Sen. Arlen Specter (D-Pa.) together raked in about $2.5 million, according to a CBS News tally by correspondent Mark Knoller. A pair of events on behalf of Senate Majority Leader Harry Reid (D-Nev.) took in $2 million, though Obama had an assist there from Bette Midler, Sheryl Crow and Rita Rudner.

A June event for the Democratic Congressional Campaign Committee and the Democratic Senatorial Campaign Committee in Washington, D.C., raised $3 million, but without the participation of lobbyists.

Those events are the only ones that the president has done directly for Congressional Democrats so far, though he has appeared at several events resulting in huge takes for the Democratic National Committee. All told, the president has raised at least $17.4 million for Democrats this year.

The budding effort to raise money and campaign directly for Congressional candidates and committees will include a stop in Connecticut on Oct. 23 to campaign for embattled Sen. Chris Dodd (D-Conn.), and the president will be in Miami on Oct. 26 for a mega-fundraiser for the DCCC and the DSCC.

A missive to Democratic supporters from Speaker Nancy Pelosi (Calif.) on DCCC stationary invites supporters to participate in a raffle for tickets to dinner with Obama and others.

“Contribute $5, $10 or more today and be automatically entered for a chance to win a trip to Miami (airfare and hotel included),— Pelosi writes. “You and your guest will be my guests for dinner with President Obama and leading Democrats from across America on Oct. 26.—

Obama will also hold a fundraiser in New York City on Oct. 20 for Bill Owens, the Democratic candidate in the 23rd district.

Owens is battling to win a Nov. 3 special election to fill the seat of former GOP Rep. John McHugh, who resigned to become Obama’s secretary of the Army.

Biden this month has already held four fundraisers for Democratic Congressional candidates. He has another slated for Reid on Friday in Nevada and an event later in the year for Dodd. Biden held six fundraising events for eight Congressional candidates in September and four events in August.