By David Nather, CQ Staff

Just a few months ago, a lot of congressional Republicans weren’t sure they wanted John McCain as their presidential nominee. Now, his campaign is rapidly building a congressional outreach machine to win their support and keep them in the fold.

It hasn’t been a perfect operation, but it has been far more successful than a lot of Republicans expected from the Arizona senator this early in the game. And it has been the kind of outreach that his Democratic rivals, Sen. Barack Obama of Illinois and Sen. Hillary Rodham Clinton of New York, can only dream of as they continue to claw and scrape their way through their party’s primaries.

“ John McCain is building much more trust among Hill Republicans than anyone thought was possible in this short period of time,” said Rep. Zach Wamp , a strong supporter of fellow Tennessean Fred Thompson during that former senator’s short-lived candidacy.

Wamp is among a handful of GOP lawmakers who have met with McCain in Washington in recent weeks. But when McCain isn’t around, which is most of the time, he has a small but growing team of campaign officials who are making the rounds for him.

Last week, for example, campaign manager Rick Davis met with Minority Whip Roy Blunt of Missouri and several other House Republicans to discuss McCain’s economic proposals and talk about strategy for the general election. Charles R. Black Jr., a lobbyist and veteran of Republican presidential politics who recently resigned as chairman of BKSH & Associates to work for McCain, has held similar meetings with Senate Republicans.

One policy adviser with increasing Capitol Hill duty is Douglas J. Holtz-Eakin, a former director of the Congressional Budget Office who’s handling many of McCain’s economic proposals. He and Davis discussed the campaign at a meeting with GOP chiefs of staff on the Hill two weeks ago, and last week he briefed several House Republicans on McCain’s economic ideas the day before the senator outlined them with a speech in Pittsburgh.

Meanwhile, the campaign’s official congressional liaison, John Green, is at the Capitol almost every day sounding out lawmakers and staff members about their concerns, previewing the candidate’s travel plans, and introducing them to policy advisers and regional campaign officials. A one-time aide to Sen. Trent Lott of Mississippi, Green is on leave from his job as the managing director of the lobbying firm Ogilvy Government Relations.

“They’ve been up here a lot over the last several weeks,” said Eric Cantor of Virginia, the chief deputy minority whip in the House, who attended the Davis meeting last week. “The purpose has been to update us in the leadership on what the senator is doing, the themes of the week, and just talk about ideas.”

They’ve also been getting help from some of McCain’s colleagues. Although none of the lawmakers have taken on any official liaison roles yet, Lindsey Graham of South Carolina fields a lot of fellow senators’ questions about the McCain campaign. (Blunt and Bill Frist of Tennessee, two years before becoming Senate majority leader, were the official liaisons between congressional Republicans and the George W. Bush campaign in 2000. Richard J. Durbin of Illinois, now the Senate majority whip, served that role for the John Kerry campaign four years ago; Ed Pastor of Arizona and Stephanie Tubbs Jones of Ohio were his House liaisons.)

Other McCain allies on the Hill now include House Minority Leader John A. Boehner of Ohio, who has stepped in to help with congressional relations and fundraising, and Sen. Kay Bailey Hutchison of Texas.

The process has had a few hiccups. House Republicans said they had been briefed in advance about McCain’s proposal last week to suspend federal gasoline taxes as a summer “gas tax holiday,” but that advance notice apparently didn’t go out to Senate Minority Leader Mitch McConnell . “I just heard about it,” the Kentuckian said at a news conference the day of McCain’s speech. “We’ll see if it has any merit.”

And the campaign doesn't seem to be doing much to get Republicans on the same page on the most divisive issues, such as climate change. Many of them disagree with McCain's support for a "cap and trade" system of limiting greenhouse gas emissions, but his campaign hasn't gotten involved in any of the Senate GOP talks in search of a consensus position. Still, that might be a smart move, some Republicans say — because it's a bit early for McCain to start twisting arms.