U.S. Senate Race: Bruce Braley, Steve King, Tom Latham or Kim Reynolds in for Tom Harkin?

The battle to replace longtime U.S. Senator Tom Harkin, an Iowa Democrat, could shake up the political landscape in Iowa.

Bruce Braley, Iowa's first district congressman and a rising star in the Democratic Party, confirmed to Facebook fans that he is considering running for U.S. Senate following the announcement that Harkin will not seek re-election after more than 40 years in Congress.

U.S. Rep. Steve King, a Republican who represents Iowa's fourth district, was already considering challenging Harkin in 2014 before the announcement he will step aside. Meanwhile, other heavyweights for the GOP are also in the mix. Some are pointing to Lt. Gov. Kim Reynolds, and Iowa's third district congressman Tom Latham.

Republicans, eager to avoid the missteps of the more outspoken conservative candidates nominated in recent years, may coalesce around Lt. Gov. Kim Reynolds or U.S. Rep. Tom Latham, who represents Des Moines and is a close friend of House Speaker John A. Boehner (R-Ohio).

The election could prove to be a gut check for the GOP. There's already a battle within the party between Tea Partiers and more centrist Republicans.

The Tea Party favorite King is an outspoken conservative who is consistently at the center of a firestorm over controversial statements. Will Republicans risk an implosion along the lines of Todd Akin or Richard Mourdock?

Latham and King both fended off tough challenges in November to gain re-election to Congress.

Braley, a 55-year-old attorney from Waterloo, is fresh off a convincing defense of his House seat from a challenge by Ben Lange, of Manchester, during the election in November.

Here's what Braley said to Facebook fans:

Over the past 24 hours, I've been overwhelmed by the outpouring of encouragement and support from Iowans in every corner of the state urging me to consider a campaign for the US Senate in 2014. Iowans deserve a senator who will continue Tom Harkin's legacy of strengthening the middle class and standing up for Iowans who don't have a voice.

While Senator Harkin's shoes are impossible to fill, in the coming days my family and I will carefully weigh a possible candidacy for Senate.

The Des Moines Register reported that Braley had been consulting key Democrats about challenging for the Iowa governorship in 2014, but Braley never publicly confirmed that.

The 73-year-old Harkin told The Associated Press in an interview, "It's just time to step aside," because by the time he would finish a sixth term, he would be 81.