Barack Obama says Republican party primary 'crack-up' is not his fault

President Barack Obamacalled the fractiousRepublican primary race a "crack-up" and rejected any suggestion that it is aconsequence of actions he has taken.

Obamaweighed in on the 2016 presidential campaign during a news conference with Prime Minister JustinTrudeauat the White House on Thursday.

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Obamasaid Donald Trump's positions aren't different from those of the other Republican presidential candidates he's just more provocative in talking about them.Obama saidTrump's positions on immigration and other issues aren't that different from those of Texas Senator Ted Cruz or Florida SenatorMarco Rubio.

Obama calledthe GOP primary a "circus" and a "Republican crack-up" resulting from GOP actions. Obama saidhe takes responsibility for failing to bridge political divides, but says he has not contributed to the worsening tone of political rhetoric.

He saidhe believes the Democrats are doing a fine job of working out issues in their primary.

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Also Thursday, Obama said he'sholding out hope that "cooler heads will prevail" and Republicans will back down from their plan to block his Supreme Court nominee.

He said he's looking for a candidate with "humility," who doesn't make policy from the bench, and someone who recognizes the role judges play in protecting minorities.

Obama's top tier of candidates include Judge Sri Srinivasan of U.S. Court of Appeals for the District of Columbia Circuit, Merrick Garland, chief judge on same court, and Judge Paul Watford of the 9th U.S. Circuit Court of Appeals, according to a source familiar with the selection process. Ketanji Brown Jackson, a D.C. district court judge, is also under consideration, although a less likely option, said the source, who asked not to be identified because the person was not authorized to publicly discuss private White House deliberations.