Rep. John Boehner (R-Ohio) waded into the heated special election to succeed former Rep. Rob Portman (R-Ohio) on Tuesday, becoming the only House Member so far to throw his support to former Rep. Bob McEwen (R).

Boehner is the first Ohio Republican to endorse McEwen over Hamilton County Commissioner Pat DeWine (R), the son of Sen. Mike DeWine (R-Ohio) who started as the frontrunner in the contest but appears to be slipping with just six days before the primary.

In a statement released by McEwen’s campaign, Boehner acknowledged that it was rare for him to become involved in primaries but said he felt compelled to get behind his former colleague, whom he characterized as “the right man for the job.”

Boehner noted McEwen’s ability to recoup his 12 years of seniority in the House, if elected, something that the former lawmaker has emphasized on the campaign trail.

“Congressman Bob McEwen is the only candidate in the race that has the experience, the values and the commitment to properly represent Ohio’s 2nd Congressional district,” Boehner said.

Knowledgeable sources indicated that other Members may follow Boehner’s lead and endorse McEwen before Tuesday’s primary.

McEwen is among 11 Republicans seeking to succeed Portman, who recently became the U.S. trade representative.

In an interview Tuesday, McEwen said he is not actively seeking endorsements at this stage of the race but said that he continues to have conversations and receive encouragement from “friends.”

“I think the campaign is going extremely well and I’m looking forward to Tuesday,” he said.

Pat DeWine has the public support of Ohio Reps. Bob Ney, Steven LaTourette and Patrick Tiberi. The three Republicans were among the hosts of a Washington, D.C., fundraiser for DeWine last month. Rep. David Hobson (R-Ohio) gave $1,000 to DeWine’s campaign last week.

Boehner, first elected in 1990, and McEwen served together in the House for two years.

McEwen was defeated for re-election in 1992 and lost a 1993 special primary election to Portman.

The winner of the special GOP primary will be heavily favored in the general election. A poll conducted for McEwen’s campaign on June 1 and 2 showed the former Congressman and DeWine in a virtual dead heat.