Democrats argue that the cuts will hammer the middle class by slashing college aid, Medicaid, and food aid for the needy, and turning Medicare into a voucherlike system while giving tax breaks to the wealthy.
They plan to build their House and Senate campaigns around the proposal, much as Republicans are tying their hopes to criticism of the Affordable Care Act. Ryan's plan would gut the health law.
Moderate districts such as LoBiondo's and three others in the Philadelphia area - based in Chester, Bucks, and Burlington Counties - are considered prime battlegrounds for the competing messages this fall.
Other local Republicans - Reps. Mike Fitzpatrick of Bucks County, Jim Gerlach of Chester County, and Patrick Meehan of Delaware County - backed the plan, which passed the House, 219-205, without one Democratic vote.
LoBiondo, running in a district President Obama won in 2012, pointed to lingering unemployment in his area as a key reason for his vote.
"With double-digit unemployment in my district, further reductions in food stamps, the Children's Health Insurance Program, student loans, and other essential domestic programs vital to the families I represent is not something I can support at this time," LoBiondo said in a statement. His home county, Atlantic, had an unemployment rate of 13.1 percent in February.
Democrats quickly pointed out that LoBiondo voted for three previous versions of the Ryan budget.
"He's flip-flopping because now he's engaged in the greatest jobs program of his career, the one to save his own," said Bill Hughes Jr., who is seeking the Democratic nomination to take on LoBiondo.
Dave Cole, another Democrat in the race, wrote in an e-mail that "we need a fresh start by making investments in education and infrastructure to create jobs, not just helping Rep. LoBiondo keep his."
Similar battle lines emerged in two Pennsylvania races.
Fitzpatrick, who represents another swing district, praised the plan for balancing the budget within 10 years - "exactly what we need to create opportunity for everyone."
But Kevin Strouse, a Democrat hoping to unseat Fitzpatrick, called the vote "a slap in the face" that could make senior citizens pay more for Medicare. Strouse is competing with Shaughnessy Naughton for the Democratic nomination.
Naughton, in a statement saying the budget would strip 30 million people of health coverage while giving tax cuts to the wealthiest, said: "Those aren't my priorities and not the priorities of the people in the Eighth District."
Another Democrat, Manan Trivedi, called it "an extreme budget that would be devastating to average Americans."
Republicans who are not in Congress but are seeking House seats praised parts of the plan but hesitated to fully embrace it.
Trivedi's Republican opponent, Chester County Commissioner Ryan Costello, praised aspects of Ryan's plan - "it puts us on a path to fiscal responsibility by finally balancing the federal budget," he said in a statement - but did not endorse it.
Costello won't "speculate about what a 2015 budget will look like and he will not commit to a vote until he has examined all of the alternatives," e-mailed an adviser, Vince Galko.
Costello and Trivedi are running to replace Gerlach, who is retiring.
Tom MacArthur, one of two Republicans competing to replace the retiring Jon Runyan in a Burlington County-based district, said in a statement that he supports tax reform and spending cuts to balance the budget, but that he would not "get into hypotheticals about voting for a budget that I didn't have any role in impacting."
An aide for his opponent in the GOP primary, Steve Lonegan, did not comment on the budget.
Runyan was home recovering from surgery and did not vote, according to an aide.