Rep. Mike Ross (D-Ark.) played a major role in the health-care debate, threatening to kill the bill until concessions were made to conservative Democrats. (Melina Mara/THE WASHINGTON POST)

“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 in his prepared statement. “But ... I believe it would be impossible to successfully run for governor here at home, while effectively carrying out my congressional duties in Washington.”

The district will immediately become a top pickup opportunity for House Republicans in 2012.

“A Democrat has represented this district for more than a decade and Congressman Ross won by nearly 18 percent in 2010, one of the toughest election cycles of a generation,” said Democratic Congressional Committee Chairman Steve Israel in a statement, calling Ross a close friend. “We are confident that a Democratic candidate who reflects the district will win this seat next November.”

Ross’ departure means that the entire four-person congressional delegation will turn over in the space of four years. All three of Ross’ fellow Arkansas House members chose not to seek reelection last year, and two Democratic-held seats went Republican. Democrats also lost the Senate seat previously held by Blanche Lincoln to now-Sen. John Boozman.

A member of the conservative Blue Dog coalition in the House, Ross came into office in 2000 and has survived by cutting a decidedly conservative profile in the House. He rose to national prominence in 2009 when he threatened to kill the Democratic health-care bill unless concessions were made to conservatives.

Ross is the fourth Blue Dog to announce his retirement this year. Rep. Dan Boren (D-Okla.) is leaving Congress. Rep. Joe Donnelly (D-Ind.) is running for Senate. Former Rep. Jane Harman (D-Calif.) resigned to lead the Woodrow Wilson Center. The caucus has shrunk from 54 members in the last Congress to just 25.

Last fall, Ross faced his first real challenge since 2000 and still won with 57 percent of the vote. If he had chosen to stay in the House, Ross might have been a more serious GOP target in 2012. With Ross gone, Democrats will have a very hard time holding their only remaining House seat in this state.

“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,” said National Republican Congressional Campaign spokesman Paul Lindsay in a statement.

Ross has not been shy about his interest in higher office.

“I love this state and you know it’s no secret that I would love to possibly help lead this state at some point in the future,” he told the Democrat-Gazette in November. “Whether that's 2014 or not, I don't know.”

Gov. Mike Beebe (D) will be term limited out of office in 2014. State Attorney General Dustin McDaniel is expected to run and Sen. Mark Pryor’s name is also mentioned. There’s also a chance that former lieutenant governor Bill Halter — who challenged then-Sen. Lincoln in last year’s Senate primary, forcing her into a run-off before losing — could run.

On the Republican side, Lt. Gov. Mark Darr is considering a bid. (Darr had also talked about challenging Ross in the House in 2012.) Rep. Steve Womack is frequently mentioned as another possible candidate.

Ross’ southern Arkansas district — already trending Republican — will become more red in 2012. Ross has said he was “disappointed” in the plan but would “continue to work hard to represent the Fourth District to the best of my ability – regardless of its boundaries.”

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