Mitt Romney vowed Friday that, if elected president, he would build the controversial Keystone Pipeline linking oil deposits in Canada to refineries on the Texas gulf coast.

"I will build that pipeline if I have to do it myself," Romney said during a speech before state Republican Party leaders gathered at a retreat in Arizona.

It was Romney's first major appearance before party officials as the party's presumptive presidential nominee. But Republican National Committee chairman Reince Priebus, who was chairing the event, stopped short of formally endorsing the former Massachusetts governor as the GOP nominee, because Romney has not officially clinched the necessary number of delegates required to claim the nomination.

Romney, who took the stage to a standing ovation, delivered essentially the same speech he has given for the last two days, attacking President Barack Obama on everything from his handling of the economy to his policies on energy, health care and education.

"The president has failed," Romney said.

He took specific aim at the Democratic Party's ties to labor unions, accusing Obama of putting union heads above the needs of the American people.

"That's where they get their money," Romney said. "And that's where they pay obedience."

He accused Obama of setting the country back on foreign policy, including in the Middle East where he said the president had jeopardized the U.S.'s relationship with Israel.

"We are not any closer to peace," Romney said.

Romney stayed away from hot-button issues in which he's come under fire from members of his party—including social issues like abortion.

Instead, he kept his focus squarely on Obama. He told the audience he had met Obama at a dinner in Washington, D.C., about "four or five years ago."

"I think he's a nice person," Romney said of Obama. "I just don't think we can afford him any longer."

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