(ABC News)

GOP presidential candidate Rick Santorum lambasted Mitt Romney this morning on 'This Week," calling him a flawed candidate and asking for a one-on-one debate with the former Massachusetts governor.

"I'd love to be able to get one-on-one with Gov. Romney and expose the record that would be the weakest record we could possibly put up against Barack Obama," said Santorum. "We can't nominate such a weak candidate."

Santorum lashed out at Romney for "hiding" behind billionaires and for his similarities to President Obama.

"The more I look at the record of Gov. Romney and match it up against Barack Obama, I feel like I am doing a training run for the general election," said Santorum. "The same issues I'm out there campaigning on against Gov. Romney are the same issues I'm going to campaign against Barack Obama on.

The former senator from Pennsylvania argued that President Obama and the former governor of Massachusetts shared similar positions on health care, "cap and trade" and "the bailouts."

"Unfortunately, Gov. Romney and Barack Obama are in the same place," Santorum said. "Gov. Romney's on the same page as Barack Obama on all of these issues."

"We can't be out there nominating someone who gives away the most important issues that conservatives care about in this election," said Santorum.