Donald TrumpDonald John TrumpAssange meets U.S. congressman, vows to prove Russia did not leak him documents A history lesson on the Confederacy for President Trump GOP senator: Trump hasn't 'changed much' since campaign MORE was probably never really going to run for president.

And President Obama’s epic smackdown of The Donald probably didn’t scare Trump away from the race as much as the idea of releasing his financial records did.

But through Trump, Obama sent two powerful messages: This is a game for grown-ups, and Obama’s patience for the silliness of some Republicans only goes so far.

White House officials draw little distinction between Trump and other fringe candidates such as former Sen. Rick Santorum (R-Pa.) or Rep. Michele BachmannMichele BachmannBachmann: Muslim immigrants trying to undermine Western civilization Religious leaders pray over Trump in Oval Office 'Real Housewives' producer 'begging' Conway to join cast MORE (R-Minn.), but it seems clear Trump touched a nerve with Obama.

Obama, like many of his predecessors, has a thin skin when it comes to amateurs questioning his administration. At the White House correspondents dinner, while Obama was whipping the crowd into laughter at Trump’s expense, there was a steely edge to the president’s voice.

Watch it again. Obama is chuckling, but his stare could cut glass. 

It is easy to forget sometimes, with high unemployment and the constant criticism from Republicans, that Obama is a master political pugilist. 

He’s the same man who outdueled and outlasted Hillary ClintonHillary Rodham ClintonAssange meets U.S. congressman, vows to prove Russia did not leak him documents High-ranking FBI official leaves Russia probe OPINION | Steve Bannon is Trump's indispensable man — don't sacrifice him to the critics MORE and the establishment Democratic Party. He is battle-tested, hardened and, most damaging to his opponents, presidential.

The race for the presidency, despite all its quirks and entertainment, is a game for adults. That’s what Obama wants to remind voters every day.

Budget fights, terrorist threats and seemingly endless energy crises and natural disasters — the constant life-and-death drumbeat is what makes presidents hard to beat. It’s also what makes them testy when also-rans come calling with silly issues and attention-grabbing claims.

And it takes one act of presidential decisiveness, in this case taking out Osama bin Laden, to remind everyone that the stakes are high and the presidency is not a reality show.

“In this instance I think the timing of [Osama bin Laden’s killing] played a large role in that it reminded the media that their obsession with Trump was ridiculous,” said Democratic strategist Karen Finney, who is also a columnist for The Hill. 

White House officials concede privately that they have no idea what the 2012 race will look like and are under no illusions about how tough the general election will be. They know the country is nearly evenly divided, and that no matter which Republican crawls out of what is sure to be an entertaining primary season, the candidate will start out at close to 50 percent. 

Trump was an easy target, and in some ways the White House might end up missing The Donald, whose entry into the race helped Obama by making his other erstwhile challengers seem small. 

And some of those left in the field are off to stumbling starts. 

Less than a week into his candidacy, former Speaker Newt Gingrich (R-Ga.) came under attack on Monday for his criticism of the House GOP budget, specifically its proposed reforms to Medicare. Gingrich said it was a radical change and described the reforms as “right-wing social engineering.” 

House Budget Committee Chairman Paul RyanPaul RyanGOP chairman to discuss Charlottesville as domestic terrorism at hearing Trump’s isolation grows GOP lawmaker: Trump 'failing' in Charlottesville response MORE (R-Wis.) fired back that with “allies like that, who needs the left?” A day later, House Majority Leader Eric CantorEric CantorEx-RNC spokesman: After Trump remarks how can I tell minorities to vote GOP Kelly’s challenge? Bringing stability to Trump White House Special interests hide behind vets on Independence Day MORE (R-Va.) said he would reserve judgment on whether Gingrich was finished. 

The Republican infighting on Medicare is reassuring to an administration that feels it is back on its feet. 

Don’t look for the president to focus his guns on other primary candidates the way he did Trump. That would make it too easy for his opponents, and Obama and his team are happy to watch the field eat itself. 

Sue Dvorsky, chairwoman of the Iowa Democratic Party, said the rest of the GOP field was “given a free ride” while Trump sucked up media oxygen. Now they will find the spotlight even brighter. 

Whoever does emerge to take on Obama will receive the same lessons Trump did: Obama is a fierce campaigner, and the nation’s grown-up-in-chief has little patience for sideshows.

The man running for another four years in the White House is no joke. If Republicans want to win, there had better not be any confusion about whether their candidate is. Otherwise, as he has done before, Obama will have the last laugh.

Youngman is the White House correspondent for The Hill.