Washington ? Democrat John Kerry’s campaign has begun background checks of top running mate prospects, including Dick Gephardt, John Edwards and Iowa Gov. Tom Vilsack, while other hopefuls anxiously await word that they’re worthy of a Washington “vetting.”

Several Democratic officials familiar with the selection process said Wednesday that background checks had been under way for several weeks. The officials, speaking on condition of anonymity, said individuals other than Gephardt, Edwards and Vilsack were under consideration, but they would not identify them.

The candidates are known only by Kerry, a handful of advisers and a team of lawyers conducting background checks that are described as unusually thorough.

Gephardt, a Missouri congressman, and Edwards, a North Carolina senator, challenged Kerry for the Democratic nomination. Vilsack is a two-term governor whose wife, Christie, helped Kerry to a surprise win in the Iowa caucuses.

A senior Iowa Democrat, speaking on condition of anonymity, said Vilsack had submitted financial information to Kerry’s search team and had been told to expect a more thorough review, called “vetting” in Washington parlance.

The man heading the search, Jim Johnson, has spoken with dozens of party leaders about the process and prospects.

Officials who have talked to Johnson said he had expressed interest in Vilsack along with others, including Sen. Evan Bayh of Indiana and former Sens. Bob Kerrey of Nebraska and Sam Nunn of Georgia.

Besides Vilsack, several top Democratic officeholders are preparing for a background check — either because they’ve been told by the Kerry team to expect one or they hope to be subjected to the process. Vice presidential “vetting” is a status symbol in Washington, so much so that politicians have been known to claim they’re on the list even if they’re not.

Democratic presidential candidate Sen. John Kerry speaks to an audience at Washtenaw Community College in Ann Arbor, Mich., during campaigning Wednesday.

Kerry could try to balance his liberal record with a moderate such as Bayh. He could opt for a candidate from a swing state, such as Govs. Bill Richardson of New Mexico or Ed Rendell of Pennsylvania.

With blacks complaining about the lack of minorities on his campaign team, Kerry might be tempted to choose a civil rights hero such as Rep. John Lewis, D-Ga. Among the women he could consider are Kansas Gov. Kathleen Sebelius or former New Hampshire Gov. Jeanne Shaheen, Kerry’s campaign chairwoman.