(CNN) - Fresh off a beachside vacation, Vice President Joe Biden resumed his campaign trail attacks Monday, this time with a new target in the mix.
Biden, at an event in Durham, North Carolina, argued the decision to pick Rep. Paul Ryan as Mitt Romney's running mate offers a "stark choice" for voters this fall.
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"The differences couldn't be more clearly laid out through the selection than you're going to hear," Biden said.
Biden called Ryan on Sunday to congratulate the Wisconsin congressman, who was announced as Romney's No. 2 at a campaign even in Norfolk, Virginia the day prior. But the vice president said the move to put Ryan on the ticket further clarifies the differences between the two campaigns this fall.
"These are stark, stark choices," Biden said.
Democrats have since pounced on the running mate pick, using the House budget committee chairman's controversial budget plan as a way to paint a Romney presidency as a threat to popular entitlement programs, like Medicare and Social Security.
Ryan's $3.5 trillion budget proposal, first introduced in 2011, includes the provision that Medicare-approved private insurers would one day compete with traditional Medicare on an exchange. The proposal would not affect Americans currently over age 55. The plan's opponents, however, say that would increase the financial burden on senior citizens.
In his remarks Monday, Biden refrained from digging too far into the so-called Ryan plan, instead using the opportunity to tie Romney with House Republicans, at large.
"Congressman Ryan has given definition to the vague commitments that Romney's been making. There's definition to it now," Biden said. "It's clear. Congressman Ryan and the Congressional Republicans…have already passed in the House what Governor Romney is promising to give the whole nation."
The vice president countered the idea that the policies promoted by a Romney-Ryan White House would offer bold solutions.
"What's gutsy about giving millionaires another tax break, what's gutsy about gutting Medicare, Medicaid, education? What's gutsy?" Biden said.
Defending his proposals, Ryan said Sunday his plan would retool Medicare so that it remains financially soluble for future generations.
"My mom is a Medicare senior in Florida," he said in an interview with CBS News. "Our point is we need to preserve their benefits, because government made promises to them that they've organized their retirements around."
Romney has in turn embraced Ryan's budget plan in the past, comparing them to some of his own economic policies. The presumptive GOP nominee, however, has not made Ryan's plan a part of his platform in the 2012 campaign, and in a set of campaign talking points obtained by CNN on Saturday, surrogates are reminded, "Of course they aren't going to have the same view on every issue."
Responding to the speech, Romney's campaign said Biden "doubled down" on what it called the "failed policies" of the Obama administration.
"Vice President Biden today doubled down on the same failed policies that have resulted in skyrocketing debt, higher taxes and record job losses," Romney spokesman Ryan Williams said in a statement. "The Romney-Ryan ticket will lay out a bold vision for our country and promote commonsense policies that will create jobs, help the middle class and turn around our struggling economy."
But the vice president on Monday argued Romney's choice of Ryan will turn off voters in the end, arguing the selection represents a move further to the right within the Republican Party.
"Folks, this ain't your father's Republican Party. It's not even Governor Romney's father's Republican Party," Biden said, referring to the late George Romney, former Michigan governor and one-time presidential candidate.
Biden's speech came shortly after President Barack Obama delivered jabs against Ryan, warning an Iowa crowd about the congressman's position on the controversial farm bill.
"I am told that Governor Romney's new running mate Paul Ryan might be around Iowa the next few days. He is one of the leaders of Congress standing in the way. So, if you happen to see congressman Ryan tell him how important this farm bill is to Iowa and our rural communities," the president said.
- CNN's Kevin Liptak contributed to this report.