When Minnesota fifth-grader Tyler Sullivan skipped school to attend an campaign event with Barack Obama Friday, the president wrote his teacher a note which read: “Please excuse Tyler.... He was with me!”

So what explains Obama’s unexcused absence from the Wisconsin recall election?

The president was just a short helicopter ride away from the Badger State this weekend. He attended three events in Minnesota and then traveled to nearby Chicago to take some time off in his home state. But he didn’t come to Wisconsin. In fact, Obama hasn’t set food in Wisconsin for months. Why?

The answer is inescapable: Barack Obama is afraid of Scott Walker.

Obama is still popular in Wisconsin. According to a recent Marquette University poll, the president enjoys a 52 percent approval rating and leads Mitt Romney 51-43 among likely voters in the state — a comfortable 8-point margin. So why not spend some of that political capital to help Democrat Tom Barrett defeat Walker on Tuesday?

After all, wasn’t the Walker recall supposed to be the great liberal cause of 2012? When Walker pushed through collective-bargaining reform over the objections of Wisconsin Democrats, the Left warned that conservatives had gone too far. Wisconsin was a union state, they said, and in taking on the public-sector worker unions, Republicans had dug their own political grave. Moreover, Obama had promised to stand with the unions. During the 2008 campaign, Obama declared “[I]f American workers are being denied their right to organize when I’m in the White House, I will put on a comfortable pair of shoes and I will walk on that picket line with you as president of the United States.”

But when the fight came, and the unions called, Obama failed to show up.

Not only did Obama not show up, his campaign is desperately trying to distance him from the Wisconsin recall effort. As Obama deputy campaign manager Stephanie Cutter put it last week, “This is a gubernatorial race with a guy who was recalled and a challenger trying to get him out of office. It has nothing to do with President Obama at the top of the ticket.”

Sorry, Stephanie, it has everything to do with President Obama at the top of the ticket. It is precisely because Obama remains popular in Wisconsin that he has not come to campaign for Walker’s opponent. Walker is leading Barrett 52 to 45 percent — virtually the same margin by which Obama is leading Mitt Romney. That means there are a significant number of independents in Wisconsin who support both Scott Walker and Barack Obama. The president does not want to alienate those voters by getting into a fight with Walker. The last thing Obama wants is to force those Walker-Obama independents to choose.

But there is someone who would love to force them to choose: Mitt Romney. And that is precisely why Romney may put Scott Walker on the GOP ticket this November.

A victory tomorrow would make Walker the instant front-runner for the GOP vice presidential nod. Walker has a great story to tell. He took on the public-sector unions and did not back down in the face of protests, civil disobedience and the spectacle of Democratic state legislators fleeing across state lines to avoid casting their votes back home. By standing firm, he succeeded in implementing collective-bargaining and other common sense reforms that have saved Wisconsin taxpayers more than a billion dollars — turning a record $3.6 billion budget deficit into a $154 million surplus. And he did it while cutting property taxes and creating a business-friendly environment that has produced more than 35,000 new jobs since he took office. All this makes Walker the national poster child for taming out of control budgets.

It has also made Walker a hero to the conservative grassroots that Romney needs to energize. By turning Walker’s recall into a national cause, Wisconsin Democrats gave Walker the opportunity to rally conservative activists across the country and build a national fundraising network that has pulled in more than $31 million — nearly triple the $11 million fundraising record he set in his 2010 race. Walker is now a national political figure who has at his disposal a well-oiled political operation that could help Romney-Walker win not only in Wisconsin but across the United States.

Putting Walker on the GOP ticket would make Romney instantly competitive in Wisconsin. And it would force President Obama to spend time and resources defending a state he expected to be an easy win in November. Even if Obama succeeded in narrowly holding Wisconsin, the fight for the Badger State would divert precious resources from other battleground states. And if the Republican ticket did pull an upset in Wisconsin, Obama’s chances for a second term would be slim to none.

Strangely, the National Journal’s latest “Veepstakes Power Rankings” do not even list Walker as a dark-horse candidate for the vice presidential nomination, much less one of its top-10 contenders. In fact, a win tomorrow should put Walker at the head of the pack. That is why the thought of a Romney-Walker ticket — and losing Wisconsin for the first time since Ronald Reagan’s 1984 landslide — strikes fear in the hearts of Team Obama.