Former Rep. Mark Neumann has picked up another high-profile endorsement in his quest for the Republican Senate nomination in Wisconsin.

Sen. Jim DeMint (R-S.C.) today emailed members of his Senate Conservatives Fund to announce his support for Neumann’s bid.

“If Mark Neumann is elected, there is no question he will fight for the principles of freedom that make America great,” DeMint wrote.

Like the support of other national conservatives Neumann has received, the DeMint email was as much against former Gov. Tommy Thompson (R) as it was pro-Neumann. That Republican primary, which also includes state Speaker Jeff Fitzgerald, is one of the nation’s most hotly contested GOP primaries.

DeMint described Neumann as a “rock-solid conservative” and called Thompson’s record “liberal.”

DeMint said that he sought feedback from the fund’s members, and an “overwhelming response demonstrates support for Neumann’s campaign.”

Neumann also is backed by the Club for Growth and conservative Sens. Rand Paul (R-Ky.) and Tom Coburn (R-Okla.).

The winner of the GOP primary is likely to face Rep. Tammy Baldwin (D-Wis.) in the general election.

Sen. Herb Kohl (D) is retiring, and Roll Call rates this open-seat race a Tossup.

Neumann is the fourth Republican candidate to receive an endorsement from the DeMint group, which proved influential in a number of primaries during the 2010 cycle. The others are former Texas Solicitor General Ted Cruz, Ohio Treasurer Josh Mandel and Nebraska Treasurer Don Stenberg.