The Republican presidential primary season was expected to provide a months-long Obama-bashing session, with the winner being the man or woman who best combined attacks on President Obama with a cogent argument for how he or she could defeat him in November 2012.

That might still happen. But for now, Obama’s influence has been felt in a different way: through complicating the race for several potential Republican candidates.

By releasing his birth certificate and then mocking Donald Trump at the White House Correspondents’ Association dinner a few days later for igniting the controversy in the first place, the president effectively ended the real estate mogul’s brief flirtation with running.

Other Republicans have suffered from an Obama problem too. The president’s aides last week enthusiastically linked the health care plan then-Massachusetts Gov. Mitt Romney signed in 2006 with the federal one adopted four years later, while Romney devoted a speech to trying to separate the two.

The president himself has openly suggested Jon Huntsman’s service in the administration as ambassador to China could complicate the former Utah governor’s presidential aspirations.

Sharp attacks by the White House have put Rep. Paul Ryan (R-Wis.), one of the GOP’s rising stars, on the defensive about his plan to reform Medicare.

In his campaign fundraisers, Obama constantly argues that he is focused on governing now, leaving the campaigning to his Chicago-based reelection operation. White House press secretary Jay Carney recently told reporters that he had not been in any meeting with the president in which the 2012 GOP field was discussed.

But little Obama says happens by accident. His diatribe against Trump at the White House dinner was in a carefully written speech. A series of administration officials and allies have linked the health care law Romney adopted with “Obamacare.”

The strategy could pay major dividends for the president. If Trump had run, he would have had almost no chance of winning the GOP nomination. But his comments, from his obsession with discussing falsehoods about the president’s birth to criticizing Obama for playing basketball, would have been covered extensively in the press and forced the White House to respond.

The comments about Romney and Huntsman may be more important. If Obama and other Democrats can spread a message that the pair are too centrist, and thereby encourage Republicans to nominate other contenders, it would eliminate two of the GOP’s strongest potential candidates.

In some ways, this approach has already worked: Romney has distanced himself from a bipartisan achievement (the Massachusetts health care law) that could have been an asset in a general election.

Ryan, meanwhile, was unlikely to run for president or be tapped as vice-president in any event. But the aggressive attacks on his ideas by Democrats have turned him from a highly regarded “Young Gun” in the GOP to a more controversial figure. Another 2012 Republican candidate, Newt Gingrich, slammed Ryan’s ideas on Sunday.

Obama today

Tuesday’s meeting at the White House between Obama and King Abdullah II of Jordan will launch several days of presidential events focused on the turbulent Middle East.

Obama will give a major foreign policy speech about the Middle East on Thursday, specifically discussing the democratic uprisings of the last several months. He will meet with Israeli Prime Minister Benjamin Netanyahu on Friday and address the pro-Israel American Israel Public Affairs Committee on Sunday.

These meetings, and the speech, will show if Obama shifts from his approaches to either the Israeli-Palestinian conflict or the “Arab Spring” uprisings. Thus far, his administration has focused little attention on reenergizing the Middle East process. And Obama has avoided offering any kind of broader doctrine to connect the events in Egypt, Libya, Syria, Bahrain and other non-democratic countries in the Middle East and North Africa.