Texas Sen. Ted Cruz (R) (David J. Phillip/AP)

Despite a pledge to steer clear of endorsing incumbents, freshman Sen. Ted Cruz (R-Texas) has financially backed a handful of Senate Republicans, including fellow Texan John Cornyn, whose campaign Cruz said Friday that he would not endorse.

Cruz's leadership political action committee, Jobs Growth and Freedom Fund, made only five donations in the first six months of its existence, and all of those dollars went to incumbents. On May 10, according to Federal Election Commission records, he wrote a $2,500 check to the campaign of Cornyn, the No. 2 GOP leader in the Senate who has moved aggressively to try to ward off a potential primary challenger next year.

The conservative firebrand dished out four other $2,500 donations to incumbents that same day: Sens. Jim Inhofe (Okla.), a 19-year veteran; Mike Lee (Utah), a fellow tea party favorite elected in 2010; Jim Risch (Idaho), who is seeking his second term in 2014; and Tim Scott (S.C.), who was appointed to the Senate after Jim DeMint resigned and is running in 2014 for the remaining years of DeMint's term.

Cruz, while attending a political event in New Hampshire on Friday, told reporters that his policy was to stay out of GOP primaries involving Republican incumbents. “I think it is likely that I am going to stay out of incumbent primaries across the country, either supporting incumbents or opposing incumbents,” Cruz said.

Cruz's comments came in response to questions about whether he would endorse Cornyn. He called Cornyn a "good man" but said he would not get involved in that race or any other incumbent races. That would place Cruz in an unusual position in his GOP caucus.

Many senators and the National Republican Senatorial Committee stay out of contested primaries when there is no Republican incumbent running -- as was the case in 2012, when Kay Bailey Hutchison retired and Cruz faced Lt. Gov. David Dewhurst in a heated GOP primary. Cornyn, then the NRSC chairman, steered clear of the race, making no donations or personal endorsements despite a widespread belief that he would have preferred Dewhurst, the establishment favorite.

Yet most GOP senators happily endorse and raise money for fellow incumbents. For instance, Sen. Rand Paul (R-Ky.), whose strong tea party backing in his 2010 race has vaulted him into contention for the 2016 GOP presidential primary, has already endorsed Minority Leader Mitch McConnell (R-Ky.) and has allowed Sen. Lamar Alexander (R-Tenn.) to air ads with Paul touting their work together on fishing issues.

As for Cruz, he appears to be making a distinction between financial support and an actual endorsement. Lee, who ousted an incumbent in a 2010 primary, has been making similar distinctions. He and Sen. Orrin Hatch (R-Utah) hosted McConnell at a Salt Lake City fundraising event earlier this month, but Lee said that was not itself an endorsement.

Cruz's comments Friday are the latest in a string of moves that have irked senior Republicans, some of whom are on the receiving end of commercials run by a PAC formerly run by DeMint, in which Cruz is shown urging Congress to refuse to fund President Obama's health-care law even if it means shutting down the federal government.