Make that five Republicans who are now challenging Rep. Leonard L. Boswell (D) in Iowa’s 3rd district.

Pat Bertroche, a doctor who practices osteopathic medicine, now has candidacy papers on file with the Federal Election Commission. He had previously said that he would challenge Boswell, who’s in his seventh term in a district that includes Des Moines and some rural territory to the east.

The Des Moines Register said that Bertroche will formally announce his campaign on Friday.