On Friday, Rep. Paul Ryan (R-Wis.), in the wake of the announced retirement of Sen. Herb Kohl (R-Wis.), put out a statement, which read in part:

“I was surprised by Senator Kohl’s announcement and want to take some time over the next few days to discuss this news with my family and supporters before making any decision about how I’m best able to serve my employers in the First Congressional District, our state and nation.”

Ryan bypassed the chance to run against Sen. Russ Feingold (D-Wis.) in 2008. His decision to remain as House Budget Committee chair, a critical role this year, seems wise in retrospect. Ryan has played a critical role in taking on the president while Sen. Ron Johnson (R-Wis.) has proved to be an able conservative lawmaker.

The question then remains: If Ryan could run for Senate, why not the White House? A Senate campaign would require increased time away from family and the House. A Senate campaign would risk leaving him with no elected position. A Senate campaign would fuel accusations that his House work is motivated by a lust for higher office. A Senate campaign isn’t a necessity; there are other able contenders.

You see, each of the excuses often advanced for not running for the presidency applies equally to a Senate run.

As for his job as House Budget Committee chair, the hard work is frankly mostly done. The budget was passed, the argument has been joined. Obama and the Democrats are uninterested in a grand deal, and it’s quite possible there will be no budget at all this year or next.

In truth, a presidential run makes a lot more sense for Ryan than does a Senate race. Ryan is already the de facto leader of the Republican Party on the most critical issues of the day. If he’s concerned about spending time with his family, what better way and better time (when they are little and not distressed teenagers thrown into the national spotlight) to bond with them than a family ad­ven­ture seeing America followed by a job where dad could work from home? While there are many potential candidates for the Wisconsin Senate seat, who among the current presidential contenders is really up to winning and then governing? A new poll shows a plurality of GOP voters don't think any of them is. (“Some 45 percent now say they’re dissatisfied with the GOP candidates who have declared or are thought to be serious about running, up from 33 percent two months ago, according to an Associated Press-GfK poll. Just 41 percent are satisfied with the likely Republican field, down from 52 percent.”)

One Senate seat is not vital to the republic, but Ryan himself has made the case how critical it is to address our looming debt crisis now. Without the White House and without someone exceptionally capable to advocate for it, it’s hard to see how the “The Path to Prosperity” is ever going to be enacted. I’m at a loss to think of another Republican who can bring together Tea Partyers, wonks, social conservatives, hawks, libertarians, Wall Street and Main Street Republicans and connect with a new generation of Republicans.

In a very practical sense, the question for Ryan is: Why not give his party and the country six months (September 2011 to February 2012)? By then he’ll either have failed to catch fire or he’ll have a clear path to the presidential nomination. Six months. Twenty-four weeks. For a politician constantly at work in Congress, in town halls and in media appearances, that doesn’t sound like that much. (In fact, I would venture that his schedule is more rigorous now than the average presidential contender’s.)

You see, there is no good reason for Ryan to avoid a presidential run. Sometimes, if you don’t see the opening and seize it, a better one never comes along. Bill Clinton understood this in 1992.

There is a lot of buzz that Indiana Gov. Mitch Daniels (R) may finally throw his hat into the ring. Ryan and his staff may think, “Well, Mitch can do it, we don’t have to.” Whatever you think of Daniels, he’s no Paul Ryan. Candidates aren’t interchangeable, least of all these two.

It’s apparent that Daniels (most recently in suggesting he’d take the pro-choice, anti-Iraq surge, pro-North Korea engagement, pro-2006 Palestinian election, Condi Rice as a vice presidential choice) is hobbled, at the very least, by a tin ear and lack of sympatico with the GOP base. Daniels is older than Ryan (hence less attractive to young voters and less able to paint Obama as old-hat, the defender of the status quo) and less acceptable to hard-core conservatives. If he’s serious about cutting defense and pulling back from America’s commitments in the world, Daniels will (in a way the internationalist, pro-defense Ryan would not) take the party and potentially the country down a dangerous road. Daniels has already expressed a willingness to consider tax hikes; Ryan has ruled them out.

In sum, the notion that Ryan could let Daniels handle the presidency while he inches up the political ladder with a Senate run is foolish. To be honest, even if Ryan doesn’t run for the White House, he should forget about the Senate. He is far more influential and valuable to the conservative movement, his party and the country as House Budget chair than as a freshman senator.

To paraphrase the Jewish sage Hillel, if not Ryan, who? If not now, when?