One of the two Republicans challenging freshman Rep. Walt Minnick (D-Idaho) is ending his 2010 campaign in the 1st district.State Rep. Ken Roberts (R) said in a statement Tuesday that he was withdrawing “with great reluctance— because of an unspecified and “unexpected health issue that has affected my candidacy and hampered my ability to make this run.—“I feel that it is my responsibility to my family to step out of the race at this time and concentrate on my health,— Roberts said.Roberts’ withdrawal leaves Vaughn Ward, a former Senate aide and CIA employee who served in Iraq with the Marine Corps, as the only Republican challenger to Minnick. Ward has been talked up by the National Republican Congressional Committee in Washington and has been viewed as the national party’s top choice in the race.Ward entered the race months before Roberts and raised four times as much as Roberts, whose campaign manager resigned Nov. 5 because he felt Roberts wasn’t raising enough money.Roberts said the Republican primary could include more candidates. Former Rep. Bill Sali (R), whom Minnick defeated in 2008, is weighing a comeback.Ward on Tuesday announced an endorsement from the American Conservative Union.Minnick has often opposed his party on major votes as he prepares to seek re-election in a strongly conservative district that includes Idaho’s Panhandle and part of Boise.