Instead of sitting out the primary elections, plenty of lawmakers are trying to help pick winners by giving to their preferred candidates — particularly in Senate races, which tend to take shape earlier in the election cycle than House races.

Those donations can be potent because the recipients can parlay those endorsements into more financial and political support.

And the money can be pretty good, too, since many members of Congress have organized leadership political action committees, fundraising vehicles that can give $10,000 to a candidate’s campaign committee — $5,000 apiece for the primary and the general election. That’s more than twice the $4,800 limit that an individual donor can give to a candidate’s campaign committee.

In the race to succeed Sen. Sam Brownback , R-Kan., who is running for governor, there isn’t much difference on policy issues between Reps. Jerry Moran and Todd Tiahrt , the two contenders in the GOP primary. But each can point to backers who are in Congress or recently served.

Moran received a $5,000 contribution from the political action committee of Arizona Sen. John McCain , the 2008 Republican presidential nominee, who endorsed Moran in September.

Moran, a member of the Agriculture Committee who represents a vast rural district, also received contributions from the leadership PACs of Sen. Mike Johanns , R-Neb., a former Agriculture secretary, and Sen. Richard M. Burr , R-N.C.

Tiahrt received third-quarter contributions from the leadership PACs of Rep. Mike Rogers , R-Mich., former Sen. Rick Santorum, R-Pa. (1995-2007), and former Rep. Mike Ferguson, R-N.J. (2001-09)

McCain has also waded into the crowded Republican primary in the western and central Kansas district that Moran is leaving open. McCain’s leadership PAC cut a check to Rob Wasinger, a former aide to Brownback, who also sought the GOP presidential nomination that McCain won.

In Florida, where appointed GOP Sen. George LeMieux is not running in the 2010 election, Gov. Charlie Crist has won the lion’s share of money that the party’s membership in Congress has donated. In the Republican primary he faces Marco Rubio, a former state Speaker. Crist is backed by the National Republican Senatorial Committee and Senate Minority Leader Mitch McConnell , R-Ky., among others.

Rubio, who is running as a more conservative alternative to Crist, has backers in Sen. Jim DeMint , R-S.C., and Rep. Ginny Brown-Waite , R-Fla.

On the Democratic side, Rep. Kendrick Meek has effectively sewn up his party’s nomination. But Rep. Corrine Brown drew contributions from some members of Congress after she initiated an exploratory committee in early June, which she terminated in October.

Brown got contributions from the leadership PAC of Democrat Donna Edwards of Maryland and from the campaign committees of Reps. John Lewis of Georgia and Grace Napolitano of California.

Yet Meek continued to rake in contributions from Democratic members even after Brown began her exploratory effort. One of his biggest backers is Rep. Debbie Wasserman Schultz of Florida, who gave to Meek’s campaign from her personal campaign committee and her leadership PAC.