Updated

"Who's going to run?"

This is the most asked question in Iowa political circles these days. Tom Harkin's decision to bow out after five terms in the U.S. Senate caught the state by surprise. Prior to Saturday, Iowa Democrats were mostly caught up with finding a candidate to take on Republican Gov. Terry Branstad in 2014.

Most of that speculation had centered on Democratic Rep. Bruce Braley. Braley, in his fourth term in the U.S. House has captured the imagination of a number of Democratic leaders statewide. His progressive voting record had drawn comparisons to Harkin. Even Branstad himself seemed to be sizing up Braley in a recent TV appearance when he noted, "Well, you know, I'm a very competitive person and I've been in 12 contested elections and I have never lost."

Now, Braley says he's conferring with his family on what to do now that Harkin's seat is open.

That's just one family discussion about a Senate campaign. The other is likely happening over at the Vilsack household.

Former first lady Christie Vilsack did herself a lot of good in her 2012 campaign against Republican Rep. Steve King. Vilsack ultimately lost, but the campaign was a win-win for her anyway. Making King run a real race against a real opponent scored a lot of points among Iowa Democrats. It didn't hurt either that coverage of the race in-state helped remind people that Christie Vilsack was a campaign veteran even though it was the first time her name was on the ballot.

While her husband, then-Governor Tom Vilsack, stayed away from endorsing presidential candidates coming to Iowa to collect caucus votes, Mrs. Vilsack did endorse. Her selection of John Kerry in 2004 helped spur his late charge in Iowa.

And now, Mrs. Vilsack has something arguably no other recent Iowa Democratic candidate has -- name recognition in eastern and western Iowa. Vilsack was raised in Mount Pleasant in eastern Iowa. Her 2012 campaign was in the 4th Congressional District which is largely west of Des Moines.

Don't forget Mr. Vilsack here. There were plenty of Iowa Democrats who were disappointed that the governor at the time did not run for a third term. He instead decided to mount a presidential campaign in 2007, but did not make it to the 2008 caucuses against a field which included future two-term President Barack Obama.

Any combination of Vilsack-Braley or Vilsack-Vilsack at the top of the Democratic ticket is likely to make the party faithful eagerly look forward to the gubernatorial and senatorial campaigns.

On the Republican side for Senate, there is potentially a long list of candidates.

There is immediate belief that Rep. King will jump in. He may, however, be waiting on fellow-Republican Rep. Tom Latham to make up his mind. Latham defeated Democratic Rep. Leonard Boswell last year in a member-on-member race caused by redistricting. Latham is held in very high esteem in Republican circles. One longtime operative believes if Latham get in, many others will stay out.

Barring a Latham candidacy, other names getting tossed around include a trio of Iowa Republicans who've won statewide election: Lt. Gov. Kim Reynolds, Secretary of State Matt Schultz and Iowa Agriculture Secretary Bill Northey.

There's also Matt Whitaker, attorney and former Bush administration U.S. Attorney in Iowa. It doesn't hurt that Whitaker played tight-end for the Iowa Hawkeyes in the team's last Rose Bowl appearance ... in 1991.

Potential Republican candidates includes social conservative advocate Bob Vander Plaats, state Sen. Brad Zaun and a pair of state party officials -- Iowa GOP Chairman AJ Spiker and Co-Chairman David Fischer, both of whom were with Ron Paul's 2012 White House campaign.