Updated: 1 p.m.

Six-term Rep. Mike Ross (D-Ark.) announced Monday that he will not run for re-election next year — ahead of a 2014 gubernatorial bid that he is mulling and most observers expect him to launch.

“I have received a lot of encouragement to run for Governor of Arkansas when Governor [Mike] Beebe’s [D] term ends in 2014,” Ross said in a statement. “I’ve always been very upfront and honest in the fact that, as a fifth generation Arkansan, I love our state and would like very much to help lead it at some point in the future. Whether I run for Governor in 2014 is a decision I have not yet made and won’t make until sometime after my term in this Congress ends.”

Ross said that if he were re-elected to another term, “it would be impossible to successfully run for Governor” in Arkansas while being a Congressman in Washington, D.C.

Army veteran and business consultant Tom Cotton, Lt. Gov. Mark Darr and Beth Anne Rankin, Ross’ 2010 opponent, are three potential GOP contenders in the 4th district. College Chancellor Chris Thomason, state Rep. Bruce Maloch (D), U.S. Attorney Conner Eldridge and state Sen. Gene Jeffress are potential Democratic contenders for the open seat.

Ross is the latest member of the conservative Blue Dog Coalition to announce he’s leaving the House. He joins Rep. Dan Boren (D-Okla.), who said earlier this year this would be his last term. The ranks of the Blue Dogs were hit hard by the 2010 elections — the group was cut roughly in half by retirements and defeats.

Ross was re-elected last cycle with 58 percent of the vote. He voted with his party only 84 percent of the time in 2010, according to a CQ Vote Study, and he was one of 19 Democrats not to vote for Nancy Pelosi (D-Calif.) as Minority Leader at the beginning of this Congress.

Republicans had expected to target Ross this cycle. They were buoyed by the fact that redistricting made the redrawn 4th district more favorable to Republicans.

“Mike Ross is saving himself the task of defending the indefensible policies of his party in what would have been the toughest race of his career,” National Republican Congressional Committee Communications Director Paul Lindsay said in a statement. “He may be the last Democrat in Arkansas, but he won’t be the last Blue Dog to throw in the towel.”

In light of this now being an open-seat race in 2012, Roll Call is changing the rating from Likely Democratic to Leans Republican.