Topeka — Tea party and conservative groups are sustaining challenger Milton Wolf in the final days of his campaign to unseat U.S. Sen. Pat Roberts in the Republican primary in Kansas, and Roberts told a radio interviewer Monday that the Leawood radiologist can’t win the November general election.

Finance reports showed that in the previous week, three groups spent $219,000 on mailings and television ads to boost Wolf’s campaign and that his fundraising largely ceased. Meanwhile, Roberts’ campaign, which has had a sizeable and consistent fundraising advantage, reported receiving nearly $81,000 in cash contributions in the last four days of July.

The primary is today. Roberts’ campaign has blanketed statewide television with ads questioning Wolf’s judgment for posting X-ray photos of fatal gunshot wounds and other serious medical injuries in 2010 on a now-disabled Facebook page, with dark-humor commentary. Roberts said on Topeka radio’s WIBW NewsNow at Noon that he is the only GOP candidate who can win in November.

“Quite frankly, I think my opponent cannot be elected in the general election, so a vote for Wolf, basically, would be a vote to send a Democrat to Congress in the Senate,” Roberts said.

Wolf spokesman Ben Hartman dismissed the comments as statements from “a desperate candidate who is in free-fall.”

Roberts and Wolf are on the GOP primary ballot with two lesser-known candidates. Shawnee County District Attorney Chad Taylor and Patrick Wiesner, a Lawrence attorney, are seeking the Democratic nomination, and Greg Orman, an Olathe businessman, is running as an independent. Republicans have won every U.S. Senate race in Kansas since 1932.

Roberts is seeking his fourth, six-year term in the Senate. Wolf has portrayed Roberts as out of touch, attacking him for owning a Washington-area home while listing his official residence as rented space in the Dodge City home of two supporters.

The two candidates had rallies Monday in the Kansas City suburbs of Johnson County, key territory in any statewide race. It’s the state’s most populous county and home to nearly 174,000 registered Republicans, more than 20 percent of the statewide total.

Meanwhile, Hartman said Wolf has stopped raising money because he’s focusing on getting his message out in the final days of the campaign.

A political action committee associated with the Washington-area Senate Conservatives Fund reported spending more than $75,000 on Friday to continue anti-Roberts television ads. The Tea Party Patriots Citizens Fund also reported spending $89,000 to produce and broadcast a television spot criticizing Roberts.

And a New Orleans-based group, Geaux PAC, reported spending $55,000 on direct mail and “digital advertisement,” though its treasurer in Washington did not immediately return a telephone message seeking more information.