Wisconsin's already-crowded GOP Senate primary field may add two candidates soon: State Sen. Frank Lasee (R-Wis.) filed paperwork with the Federal Election Commission earlier this week, while muti-millionaire Eric Hovde is mulling a run.

The field already includes former Wisconsin Gov. Tommy Thompson, former Rep. Mark Neumann (R-Wis.), and Wisconsin state Assembly Speaker Jeff Fitzgerald (R).

Thompson and Neumann are considered the front-runners for the race: Thompson is well-known in the state after more than a decade as governor, while Neumann has emerged as his strongest opponent from the right.

It is unlikely that Lasee will be able to make much of an impact on the campaign. But Hovde said that should he decide to run he would spend $10 million of his own money on the race, making him an instant player.

Hovde, who recently moved back to Wisconsin from Washington, D.C., has criticized what he views as a dangerously cozy relationship between Wall Street and Washington. He could throw a wrench into the race by appealing to populists and centrist Republicans. This could hurt Thompson, who is counting on support from centrists to beat Neumann.