Senate Majority Whip Dick Durbin is going to be busy in October.

As the only senior leader of the Senate majority not running for re-election, much of the burden of actively working to elect Democratic Senate candidates falls on the Illinois lawmaker, who will travel to multiple states to boost his party’s prospects.

Durbin will also focus on his home state, where Democrat Alexi Giannoulias is seeking the Senate seat formerly occupied by President Barack Obama. Durbin hopes to help Democrats running in four competitive Illinois House seats as well.

Republicans are threatening a dozen Democratic-held Senate seats, and three members of the Senate Democratic leadership team ‘ including Majority Leader Harry Reid (Nev.) and Conference Vice Chairman Charles Schumer (N.Y.) ‘ are focused on their own races.

Durbin’s tentative schedule includes travel to a handful of states at the behest of the Democratic Senatorial Campaign Committee and significant time on the road in Illinois both with and for Giannoulias, the state treasurer who is running even with Rep. Mark Kirk (R) in an open-seat contest.

Durbin is focused on three vulnerable Democratic House seats and the race for the suburban Chicago 10th district being vacated by Kirk. Durbin is trying to help marketing executive Dan Seals, the Democrat who failed to oust Kirk in 2006 and 2008. Seals is facing businessman Bob Dold (R) in this year’s race.

Durbin is also set to attend two separate Illinois campaign events: one headlined by the president, the other by first lady Michelle Obama.

Jimmy Williams, a former Durbin aide and now a principal with Sonnenschein Nath and Rosenthal in Washington, D.C., described the Majority Whip as energetic, a ‘bulldog’ and a relentless campaigner who is an effective communicator on the stump. Durbin is one of the Senate’s more fiery liberals, but he has a friendly Midwestern demeanor and has forged friendships with many of his Conference’s moderates.

‘Dick Durbin is widely respected in the Senate Democratic caucus and, frankly, within the House Democratic Caucus,’ Williams said. ‘He has the president’s ear and is a veteran of both Illinois and national politics. That gives him the gravitas to go out there and speak on behalf of candidates and to discuss the accomplishments of this Congress, which have been overlooked and not messaged as well as they should have been.’

In 2006 and 2008, Democrats gained a total of 14 Senate seats. The Democrats were on offense, with Reid and the rest of his leadership team free to focus on Senate campaigns.

But this year, Reid is embroiled in a tough re-election battle with former Nevada Assemblywoman Sharron Angle (R), a flawed candidate who is nevertheless well-funded and giving the Majority Leader all he can handle. Reid led Angle by 1.4 points according to the Real Clear Politics average of polls taken Sept. 10 through Tuesday.

Senate Democratic Conference Secretary Patty Murray (Wash.) is facing a tough challenge ‘ at least for now ‘ from businessman and two-time gubernatorial runner-up Dino Rossi (R).

Schumer, who coordinated closely with Reid on political matters while serving as DSCC chairman during the 2006 and 2008 cycles, is focused on his own re-election as well. Schumer is safe, but Democrats familiar with his plans for October said he is treating his race as though it were competitive and plans to spend the final four weeks of the midterm campaign crisscrossing New York’s 62 counties.

That leaves Durbin as DSCC Chairman Bob Menendez’s (N.J.) top available surrogate, other than Obama and the first lady. And Menendez’s needs are expansive, as the Democrats seek to defend a dozen seats ‘ California, Colorado, Connecticut, Delaware, Indiana, Nevada, North Dakota, Pennsylvania, Washington, West Virginia, Arkansas and Wisconsin.

Other than Schumer, who has transferred more than $2 million in personal campaign funds to the DSCC, Durbin has been among the most generous with the committee, contributing at least $330,000 so far this cycle.

DSCC spokeswoman Deirdre Murphy said Durbin has been extraordinarily helpful to committee.

‘Not being on the ballot himself, Sen. Durbin’s outsized support for Democratic Senate candidates comes from a sense of responsibility to help his Democratic colleagues and challengers alike,’ she said. We are thankful for his help as we remain united in defeating extremist Republican candidates.’