(Charles Dharapak/AP)

President Obama's strategists are resurrecting criticisms of Mitt Romney from the Republican primaries and using them against the GOP presidential frontrunner as the general election campaign intensifies.

The goal is to undermine Romney among conservatives by reminding them of the doubts they've had about him all along, and to damage Romney among independents who might not have been paying attention to the campaign so far and need a primer on Romney's flaws.

Chief Obama strategist David Axelrod told reporters Monday that Romney and his allied poitical action committee have spent tens of millions of dollars blasting opponents with negative ads, which is a criticism leveled against Romney by GOP rivals Rick Santorum and Newt Gingrich in the primaries. Axelrod's point was the same as the one made by Santorum and Gingrich—that Romney doesn't have a good record to run on so he resorts to "tearing people down."

Axelrod said that while Romney was governor of Massachusetts, the state sank from 37th to 47th in job creation, the same argument made aggressively by Santorum in debates. In recent days, the Obama re-election campaign and the Democratic National Committee also have quoted Santorum as saying Romney had a very weak economic record as governor.

Santorum endorsed Romney this week, but his past criticisms live on.

The DNC also resurrected former candidate Michele Bachmann's prediction that Romney would be a sure loser in November because he doesn't show the strength of his conservative convictions. Since then, Bachmann also has endorsed Romney.

Over the weekend, Obama underscored Romney's background of wealth and privilege, as his GOP opponents did in the primaries and in various debates.

In another dig at Romney, President Obama said that "unless you're lucky enough to have parents to lend you money," federal loans and other forms of government assistance are necessary for many young people to go to college, and he pledged to continue such programs.