Saying that "urgent battles in Congress that can't wait until 2015," Representative Steve King of Iowa declined to run for the Senate seat being vacated by a retiring Tom Harkin.

Politico:

"This week, I made a simple device to put toothpaste back in the tube But a device to put the Leftist genie back in the bottle is not so simple," he said in a statement.

King is the second GOP senate prospect in as many days to announce his decision to stay out of the race: state Agriculture Commissioner Bill Northey announced Thursday that he wouldn't run, and said he hoped King would decide to enter the race.

King's name was one of the first that came up when Democratic Sen. Harkin announced his retirement earlier this year, but his ongoing indecision about the race prompted most Republicans in the state to think he was ultimately unlikely to run.

He joins a list of prominent Iowa Republican contenders who have chosen to sit out the race, including Northey, Lt. Gov. Kim Reynolds and Rep. Tom Latham.

Some Republicans in the state also believe Latham might reconsider his decision to stay out of the race.

"If you reread his note to his supporters of why he wasn't going to run for Senate, he definitely gives himself an opening to get back in if that's what he chose to do," social conservative activist Bob Vander Plaats told POLITICO earlier this week.

"Now, if King determines he's not going to run, I think the landscape has shifted ... and Tom Latham needs to reassess his interest in the race."

As previously reported by POLITICO, other Republicans who have expressed interest include Iowa Secretary of State Matt Schultz, former U.S. Attorney Matt Whitaker, state Sen. Joni Ernst and David Young, an aide to Sen. Chuck Grassley.