Led by former Minnesota U.S. Sens. Rudy Boschwitz and Norm Coleman, 16 past and present Republican senators will host a Washington, D.C., fundraiser next month for Mike McFadden, one of Sen. Al Franken's leading GOP challengers.

Set for March 5 at the National Republican Senatorial Committee, the event is the clearest sign yet that McFadden, a former investment banker, has seized the support of the GOP establishment in D.C.

With Franken rated as one of the Congress' most liberal lawmakers, his seat has long been a target for conservatives aiming to regain control of the Senate.

Along with Boschwitz and Coleman, the hosts are Senate Minority Leader Mitch McConnell of Kentucky, John Barrasso of Wyoming, Richard Burr of North Carolina, Bob Corker of Tennessee, John Cornyn of Texas, Mike Crapo of Idaho, Chuck Grassley of Iowa, Johnny Isakson of Georgia, Jerry Moran of Kansas, Lisa Murkowski of Alaska, Rob Portman of Ohio, Pat Toomey of Pennsylvania, John Thune of South Dakota and Roger Wicker of Mississippi.

McFadden's staff did not respond to questions about ticket prices for the event.

Franken defeated Coleman by the narrowest of margins in the 2008 election. By taking on a larger role to help Republicans recapture the seat, Coleman may be looking for political payback.

McFadden faces three other Republicans – state Sen. Julianne Ortman, state Rep. Jim Abeler and St. Louis County Commissioner Chris Dalberg -- for the party nomination.

While McFadden has the blessing of national Republicans, he still has to shore up his in-state support. He finished second to Ortman in the state straw polls this month and his GOP opponents and Democrats have hammered him for not participating in public debates.

Even if the McFadden doesn't capture the party endorsement this spring, he's widely expected to run in the August primary. His campaign staff has repeatedly said that he's running against Franken, not the Republican field.

With $4.8 million banked thus far for his re-election run, Franken has a considerable fundraising lead on his would-be GOP opponents. McFadden, his closest competitor in the money race, had $1.7 million cash-on-hand at the end of January.