Ever since he won a House seat in 1998 at the tender age of 28, Wisconsin Republican Rep. Paul Ryan has been seen as the party’s strongest potential Senate candidate in the Badger State.

Ryan, himself, publicly entertained the possibility of running for Senate in 2012 if the seat came open. “I’ll definitely look at that and cross that bridge when I get to it,” Ryan said in 2008.

And yet, when Sen. Herb Kohl (D) shocked the political world last Friday with his announcement that he wouldn’t seek a fifth term in 201 2 it immediately became clear that Ryan was likely to pass on the open seat race.

Ryan made it official Tuesday morning; “I believe continuing to serve as Chairman of the House Budget Committee allows me to have a greater impact in averting this debt-fueled economic crisis than if I were to run for the United States Senate,” he said in a statement explaining his decision.

So, what gives? Why didn’t Ryan run — or even, really, give the idea of running serious consideration?

There are, not surprisingly, several schools of thought on that question.

One argument is that running for the Senate presented a clear risk without genuine benefit for Ryan.

An open seat race in a presidential year in Wisconsin is a toss-up proposition — at best — for any Republican. (The last Republican to win a Wisconsin Senate race in a presidential year was Bob Kasten way back in 1980.)

That’s especially true in this election where Gov. Scott Walker’s (R) fight with labor unions over collective bargaining has turned the state into a national battleground where Democrats will go all-out to win.

“I can’t help but wonder how he would do with Obama at the top of the ticket and coming on the heels of the Walker thing,” said one senior Republican House operative.

And, for Ryan the upside of the Senate race isn’t all that high. His budget proposal has turned him into a national figure — for good and bad — and many within the party see him as their best option to engage President Obama in a battle of ideas in the coming months.

“He has a strong enough following and future in his current position and does not need the exposure that the Senate offers,” said one Republican House strategist about Ryan’s decision. (The strategist added that Ryan had pledged not to vacate his swing 1st district unless and until he found a Republican who could hold it.)

Another argument put forward as to why Ryan so quickly took a pass on the Senate is that he has a potential path to the chairmanship of the Ways and Means Committee within the next four years. Michigan Rep. Dave Camp (R) will be term-limited out of the post at the start of 2015 and Ryan, while he is the fourth ranking Republican on the committee, is widely regarded inside the GOP conference as a favorite to ascend to the job.

GOP insiders say that Ryan has long dreamed about chairing Ways and Means — the tax writing committee in Congress — and the prospect of doing so was too appealing to pass up even for a Senate bid . Of course, there’s no guarantee that a) Republicans will still be in the House majority in 2015 or b) that Ryan will still be the golden boy who can leap the seniority chain when that time comes.

There are, of course, those less favorably inclined to Ryan who suggest his decision not to run for the Senate is evidence of his risk-averse nature more than anything else.

Ryan has either looked at or been talked about as a statewide candidate dating all the way back to 2004. He has passed every time.

“For as bold as Ryan is on policy matters, he is equally timid when it comes to politics,” said one senior Republican operative granted anonymity to speak candidly about Ryan.

Whatever the reason, Ryan’s decision not to run for the Senate in 2012 likely means that he is committing himself to climbing the House leadership ladder rather than running for statewide office.

Of course, he’s still only 41 years old, meaning that Ryan could spend the next decade running the Budget committee and, perhaps, Ways and Means comittee in the House and still be in the prime of his political career in plenty of time for future statewide runs or even a bid for national office.