The growing roster of Republican Members who have announced their upcoming retirements will affect a lot more than the makeup of the next Congress and the outcome of the 2008 elections.

It also will impact Republican lobbyists who have spent years cultivating relationships with the 15 (and counting) departing Members. Some industries and causes already are preparing to say goodbye to their longtime champions.

And some Republican lobbyists who this election cycle have opened their personal checkbooks — and those of their political action committees — to these now- departing Members privately say they are considering new etiquette territory: Is it ever OK to ask for a contribution back?

GOPers also say they expect that the recent spate of retirement announcements is just the beginning, and they are expecting more blows to their party’s current power structure.

“The impact is that it sucks,” said Todd Weiss, a Republican lobbyist who is vice chairman of Sonnenschein Nath & Rosenthal’s bipartisan public policy department. “I believe in the values and the traditions of the Republican Party. It looks like we’re going to be in the wilderness for a while, but we’ll come back.”

The retirements, which include Members who have served upward of 30 years in Congress, promise to hit virtually all sectors on K Street.

No fewer than six appropriators have said they are leaving — Reps. Ralph Regula (Ohio), Ray LaHood (Ill.) and David Hobson (Ohio) as well as Sens. Pete Domenici (N.M.), Wayne Allard (Colo.) and Larry Craig (Idaho).

Defense and military affairs lobbyists will lose a longtime advocate in Sen. John Warner (Va.), while a slew of former aides to one-time Speaker Dennis Hastert (Ill.) won’t be able to call on their old boss. And retiring Rep. Chip Pickering (Miss.), who helped craft the Telecom Act when he was a Congressional aide, won’t be there for the technology sector.

Jim Dyer, a former clerk and staff director on the House Appropriations Committee, said the losses in the appropriations area will be brutal.

“Personally, for me, I’m going to lose six good friends, six men who know how to do deals and produce good legislation,” said Dyer, now a lobbyist at Clark & Weinstock. “These are people who have tremendous institutional memory, who are respected and are people of achievements. The real loss is to the institution.”

Charlie Black, a longtime Republican lobbyist with BKSH & Associates, said that he has long gone to Regula, a key player on the Appropriations Subcommittee on Labor, Health and Human Services, and Education, with health care clients’ concerns. “He was always willing to listen to a wide range of people,” Black said. “He didn’t always support what you wanted, but you had a good sense of comfort that you were going to get a fair hearing.”

Lobbyists spend years, sometimes decades, building ties with lawmakers, ties that sometimes become friendships.

Black said he has known Rep. Jim Ramstad (Minn.) since 1978, when he met him during a campaign for Sen. David Durenberger (R-Minn.). “We’ve been friends for 30 years,” Black said. “Jim has been at Ways and Means for years and years, and been involved in trade issues. Any time you had trade matters, he was a go-to guy. He is a friend and a strong advocate of free trade.”

Frank Maisano, an energy lobbyist whose clients include Valero Energy, Southern Co. and US Wind Force, said the departure of Domenici will be a particular loss when it comes to the issues he championed.

“He’s an expert on the appropriations process, the budget and energy. He’s a triple threat,” Maisano said. “These are not easy issues. He was a person who gave serious consideration to the process and gave serious consideration to the complexity of the issues and to the need for collaboration for resolving the issues.”

As a result, Domenici enjoyed broad support on K Street, and before he announced his retirement plans on Oct. 4, he had collected a slew of checks from the D.C. lobbying sector. Lobbyists with Parry Romani, Van Scoyoc Associates, Baker Donelson, the Nickles Group and Ogilvy Government Relations, among others, all were on his donor list, according to filings with the Federal Election Commission.

Indeed, some lobbyists note privately that they are weighing their options about asking the retiring Members to return contributions.

While very few said they would be willing to take that step, they said they are keeping a close watch on more possible retirements when deciding how to dole out PAC and other campaign funds. “You want to be careful where you put your money,” one GOP lobbyist said. “We expect a lot more [retirement] announcements.”

One defense industry lobbyist said the retirements combined with more restrictive lobbying and ethics rules will make it harder to cultivate new relationships to take the place of the old ones. “We’re not allowed to take anyone out to lunch,” this lobbyist said. “A lot of our established relationships are leaving. It’s harder to get know anyone, unless we host a fundraiser for them.”

Among his donors, Pickering’s top support came from the health care, technology and lobbying sectors, according to the Center for Responsive Politics. Ralph Hellmann, the chief lobbyist for the Information Technology Industry Council, said Pickering has been a champion for his industry.

“I know just about everyone who’s retiring,” said Hellmann, a former aide to then-Speaker Hastert. In addition to Pickering, Hellmann said retiring Rep. Jerry Weller (R-Ill.), a member of the Ways and Means Committee, is a point-person for techies on trade and tax issues. “Their leadership will be missed,” Hellmann said.

David Hoppe, a GOP lobbyist at Quinn Gillespie & Associates, called the string of retirements a changing of the guards.

After wishing them well, and analyzing the political ramifications of their departures, Hoppe said, “you look at what will this mean in terms of their position on the committee, who might be the new chairman or ranking Republican, and how will the switches affect all those things.”