While promising to break from the past and change Washington, presidential candidates Sens. Barack Obama (D-Ill.) and John McCain (R-Ariz.) are relying, as previous White House wannabes have, on the advice and counsel of longtime Washington insiders.

Both presumptive nominees see their Senate colleagues as critical sounding boards for decisions about whom to choose as vice presidential running mates, as well as on campaign themes, tactics and other critical issues. This is despite repeated promises to change how Washington operates.

The candidates’ Senate friends say outreach of this sort is natural given the relationships each of them has fostered in their years on Capitol Hill and their need to maintain those alliances in an Obama or McCain White House.

The effort also shows that, unlike President Bush and former President Bill Clinton — both former governors and Washington outsiders with fewer ties to Capitol Hill — relations between the two branches might improve once a senator is installed at 1600 Pennsylvania Ave.

“Both of them are running essentially against Washington, and I think that’s great because I think that’s where the American public is today,” said Sen. John Thune (R-S.D.), a possible running mate who says he has not been interviewed for the job. “But I think it’s true that all these people here represent constituencies … and hopefully they’re able to give [the campaigns] advice based on what they’re hearing from their constituents back home.”

Obama has wasted no time reaching out to his Capitol Hill colleagues. Two days after Sen. Hillary Rodham Clinton (N.Y.) dropped her bid for the Democratic nomination, a three-member team came to Capitol Hill to seek out senators and get their input on the biggest issue facing his campaign — whom to choose as a running mate.

The team, led by Caroline Kennedy, the daughter of former President John Kennedy, and also including former Deputy Attorney General Eric Holder and Jim Johnson, the former CEO of mortgage giant Fannie Mae, spent Monday and Tuesday holding hour-long meetings with Obama’s Senate supporters and congressional leaders to discuss names and provide suggestions.

The process has been secretive, and senators were mum about which names are being considered. But according to participants, the possible nominees run the gamut from those with long careers inside Washington to governors and military officers.

Obama’s three-member team is expected this week to discuss running mates with Clinton backers, including Sen. Charles Schumer (N.Y.), the top Senate Democratic campaign strategist.

Sen. Dick Durbin, a fellow Illinois Democrat and prominent Obama supporter, said after his Tuesday meeting that the team was considering “many, many names.”

“It ranges all over,” Durbin said. “Some of them would surprise you, and some of them wouldn’t.”

Sen. Kent Conrad (D-N.D.), who met Obama’s team Tuesday, said it was “wise” to reach out to senators who have experience in working with a number of the candidates presumed to be on the short list.

“The last thing you want is a surprise,” Conrad said.

Sen. Ben Nelson (D-Neb.), who endorsed Obama in the primaries but has not yet met with the VP team, saw the outreach as a way to bolster ties with senators.

“There’s always the public-relations side of talking to a lot of different individuals,” Nelson said. “So many people like to see their names on the short list.”

Nelson, a former governor, says he is not promoting his candidacy, but he has been mentioned as a possible running mate. So have Democratic Sens. Joseph Biden (Del.), Chris Dodd (Conn.), Jim Webb (Va.), Bill Nelson (Fla.) and Clinton herself.

On the Republican side, younger governors and senators are seen as likely choices, as well as ones who could provide economic and business credentials to the ticket.

The vetting process for McCain’s running mate, however, has been much quieter, and he has not undertaken a full outreach on Capitol Hill for a No. 2. Arthur B. Culvahouse, a senior Reagan administration attorney, has led the search, as The Hill revealed last month.

Still, McCain’s team has held weekly outreach meetings and regular conference calls, seeking advice from senior members of Congress with whom the candidate barnstormed the country.

“People are not shy about offering suggestions, either,” said Sen. Sam Brownback (R-Kan.).

Senate GOP backers of former Massachusetts Gov. Mitt Romney’s unsuccessful bid for the GOP nomination are pushing their man as veep, saying his credentials as a chief executive in government and business would complement McCain’s in foreign affairs and national security.

When asked about a McCain-Romney ticket, Brownback said: “He’s very, very bright. He’s very good on economic issues. He’s polished, and I think he’s a blue-chip prospect.”

Brownback said McCain has also relied on advice from people outside Washington, such as former chief executives of Fortune 500 companies.

Tucker Bounds, a McCain spokesman, said the “only way to reform Washington and deliver change is to have information,” experience and judgment to make the right decisions.