Indeed, Romney’s financial advantage means Obama must find time in his schedule to keep personally wooing donors, even as the campaign enters a phase where he will be headlining more big rallies and other public campaign events.

Going strong so far, Republicans say they’re optimistic that the Romney campaign can keep up its fundraising prowess through the fall, and they point to the campaign’s improved use of online efforts to target independent voters, evangelicals and military voters.

‘‘We are getting an outpouring of support from, not just Republicans, but independents, Democrats and even former Obama supporters,’’ said Woody Johnson, a major Romney donor and the owner of the New York Jets. ‘‘People realize just how important this election is to get our economy going again.’’

Democrats say it’s not Romney’s campaign fundraising that worries them — it’s the influx of money from the GOP-leaning super PACs.

Two of the largest Republican Super PACS, Restore Our Future and Americans Crossroads, have raised about $122 million since the beginning of last year. Democratic-leaning groups Priorities USA Action and American Bridge 21st Century have raised about $30 million in the same time period.

Priorities is turning to President Bill Clinton — a prolific fundraiser — to help boost its totals. The former president will host an event in New York next week.

Obama, after spending two days campaigning in Colorado, will hold three fundraising events in his hometown of Chicago on Sunday, including one at his family’s South Side home. The fundraising will be followed by three days of campaigning in Iowa.

In order to compensate for the president’s divided time, the campaign is turning to a number of surrogates, including Michelle Obama, to raise money. The first lady is holding events in Jackson, Wyo., on Saturday and a family-oriented fundraiser with members of the band No Doubt at the Beverly Hills, Calif., home of lead singer Gwen Stefani.

Romney is also dividing much of his time between events with voters and fundraising. He has both fundraisers and public events in Illinois, Iowa and New York this week, then launches a four-state bus trip on Saturday through Virginia, North Carolina, Florida and Ohio.

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Pace reported from Washington. Associated Press writer Jack Gillum in Washington and Steve Peoples in Wolfeboro, N.H., contributed to this report.

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