Utah legislators are barred from raising money for any office during the annual 45-day session.
Wimmer said he will submit his letter of resignation to House Speaker Becky Lockhart, R-Provo, on Thursday. It will take effect Jan. 16. Republican delegates in southwest Salt Lake County district likely will meet to have a special election to choose a replacement by Jan. 19, according to Salt Lake County Chairwoman Julie Dole. The 2012 legislative session begins Jan. 23.
"Being a blue-collar, middle-class Utahn," Wimmer said, "I am not able to fund my own congressional race. I have to have the ability and capability to raise money."
Wimmer said his campaign raised more than $200,000 through the end of the year, meeting its goal, but he can't slow down if he is going to compete with Matheson, who had more than $500,000 in his campaign account several months ago.
"He has a massive head start," Wimmer said. "If you're running the type of race you need to run to beat Jim Matheson, an entrenched Democratic incumbent, I think it would be almost impossible to serve in the Legislature full time."
Wimmer said the decision to resign from the Utah House has been "one of the single toughest decisions that my wife and I have ever had to make," but he believes it is vital that a Republican beat Matheson, whom he blames for contributing to a growing national debt.
Wimmer becomes the third Utah lawmaker who has stepped down from the Legislature to campaign for higher office. State Sen. Dan Liljenquist, R-Bountiful, resigned last month to campaign for U.S. Senate and state Rep. David Clark, R-Santa Clara, left to run for the 2nd Congressional District.
State Rep. Stephen Sandstrom, R-Orem, who is also running in the 4th District, doesn't plan to resign. Neither do Rep. Chris Herrod, R-Provo, who will decide by the end of the week if he's running for U.S. Senate; Rep. Ken Sumsion, R-American Fork, who is running for governor; or Democratic Sens. Ross Romero and Ben McAdams, both of Salt Lake City, who are running for Salt Lake County mayor.
Katie Drake contributed to this report.
So far, two Republican candidates have said they plan to run to replace Wimmer in House District 52:
Herriman Mayor Josh Mills • announced his interest in Wimmer's seat and has a campaign kickoff planned for Saturday, where Wimmer will publicly endorse him. Mills will likely resign from his post as mayor if elected.
Dan McCay • A real estate lawyer and father of four from Riverton said he has been meeting with delegates for about a month. McCay is also the Utah director for the Washington-based activist network Freedomworks, which is a part-time post.