Jump In: Who Should Run to Replace Sen. Herb Kohl?

Big news out of Washington this week when . How big was it? "Herb Kohl" was trending on Twitter Friday. 

It took about 15 seconds for people to start offering up candidates to run for the open seat. After Sen. Russ Feingold's loss to Ron Johnson last year and Gov. Scott Walker's win over Tom Barrett, Democrats are hoping to retain the seat - and a sense that Wisconsin is still a "blue" state (or at least purple). 

Meanwhile, Republicans know they have an opportunity to sweep the top four statewide-elected offices (Johnson, Walker, and Attorney General JB Van Hollen being the other three).

Here's a look at top names in each party who may run for Senate: 

Republicans

Rep. Paul Ryan - The Janesville Republican at the top of a strong list of Wisconsin GOP candidates, but he's taken controversial stances on Social Security, Medicare and Medicaid. He's a national political star, but can he get elected statewide? 

JB Van Hollen - Wisconsin's Attorney General has won two statewide elections, which is key in a Senate race. Compared to GOP rivals he makes few political waves. 

Sen. Scott Fitzgerald - The state Senate majority leader has the ambition to run for Kohl's seat, but he's facing more immediate concerns with recall elections threatening his place atop the Senate. 

Rep. Jeff Fitzgerald - See Scott, just replace Senate majority leader with House speaker.  

Gov. Scott Walker - After presiding over sweeping changes in state government, may the governor look to take a step up to the national stage? 

Democrats 

Russ Feingold - The former senator lost to Ron Johnson last year in a tough midterm elections for Democrats around the country. Feingold is a well respected politician, but has his time passed? 

Rep. Tammy Baldwin - The Madison congresswoman is considering a run, and she'd bring a strong liberal voice to the race. But can a Madison-based candidate win statewide office? 

Tom Barrett - The former congressman and current Milwaukee mayor couldn't ignite moderate supporters against Walker last year. But at least some Walker voters are regretting their support of the union-attacking governor, and may be willing to back Barrett a second time through.