Sen. Ted Cruz (R-Tex.), who told colleagues last year that he wouldn't assist a tea party group trying to unseat GOP incumbents in primaries, is featured in another fundraising letter from a group that does the same thing.

Cruz's office notes that the group uses a public letter from the senator's office and says it has no problem with the group using the senator to raise money.

It was reported earlier this week that Cruz had written a fundraising letter for the Madison Project, a group that backs Republicans challenging Senate Minority Leader Mitch McConnell (R-Ky.) and Sen. Thad Cochran (R-Miss.). Cruz explained at the time that the letter was written last April, before he said he wouldn't get involved in primaries.

On Friday, the Tea Party Express released its own fundraising missive featuring an open letter from Cruz to tea party supporters on the fifth anniversary of the movement. The letter was released publicly by Cruz on Thursday.

The fundraising e-mail also includes a 2012 picture of Cruz in front of a Tea Party Express banner and asks supporters, "Will you be fighting with us this year in our effort to send Ted Cruz and conservatives in Congress reinforcements?"

Cruz spokeswoman Catherine Frazier said the letter is fair game.

"This is a public letter in the public domain, and it was issued far and wide as a press release," Frazier said. "Groups can do what they want with it."

Tea Party Express founder Sal Russo said he didn't seek permission to use the letter.

"I didn’t feel it was a private document that required it," Russo said.

Cruz is a vice chairman of the National Republican Senatorial Committee, which supports GOP incumbents in primaries.

The Tea Party Express has endorsed primary challengers against Cochran, Sen. Pat Roberts (R-Kan.) and Rep. Pete Sessions (R-Tex.) this year. It also features an interview with McConnell's challenger on its Web site.

It is general practice for groups featuring a member of Congress in a fundraising letter to obtain that member's permission.

Updated at 12:23 p.m.