Rep. Pete Sessions (Texas) may have to juggle the ambitions of several House colleagues in Arizona as the Senate race heats up.

Rep. Jeff Flake (R-Ariz.) announced his intention to run on Monday and is expected to leave his 6th district seat. Sessions, who chairs the National Republican Congressional Committee, called Flake a "stalwart fiscal conservative."

"Jeff has been a great friend and colleague to me, and the House will miss his principled leadership," Sessions said in a statement. "I look forward to the people of Arizona's 6th congressional district sending another Republican to Congress who will continue Jeff Flake's pursuit of smaller government and individual liberty."

Flake's Phoenix-area district has been comfortable territory for the GOP, but it may not be the only open seat the party has to defend next year. Rep. Trent Franks (R), who represents the sprawling 2nd district, could also get into the race.

And complicating matters, former Rep. J.D. Hayworth (R-Ariz.) is also mulling a run for Senate. Hayworth represented the 5th district, which is now held by Republican Rep. David Schweikert.

Sessions was once an ally of Hayworth's, even helping him financially.

Sessions donated to the Freedom in Truth Trust (FITT), which Hayworth set up in 2008 to pay down legal bills stemming from the Jack Abramoff lobbying scandal.

Hayworth came under investigation by the Department of Justice after he received campaign contributions from Abramoff and his Indian tribe clients, including in-kind use of skyboxes at sporting events. He incurred more than $170,000 in legal fees defending himself and set up a legal trust to receive donations after he left Congress. Hayworth was eventually cleared by DoJ.

Several prominent House Republicans, including Sessions, donated to the trust.

"The donation was given with the sole intent of helping a former congressional colleague with his legal defense against baseless claims," Emily Davis, a spokeswoman for Sessions, told The Hill last year. "The donation cannot and does not have any connection to political funds."

Sessions' campaign finance filing shows the $2,500 donation was made on Oct. 7, 2009 -- two days after reports surfaced that Hayworth intended to challenge Sen. John McCain (R-Ariz.) in a primary.