The reverberations on K Street are still being felt nearly a year after Sen. Arlen Specter (D-Pa.) switched political parties, with Specter loyalists maintaining their support while some big business interests and longtime Republican donors are distancing themselves.

In the year leading up to his decision to switch parties, Specter had a plethora of K Streeters hosting events for him. Republican stalwart C. Boyden Gray and National Association of Federal Credit Unions lobbyists Dan Berger, Javier Sanchez and Jennifer Wahlen were among those listed as hosts for Specter events.

But now several high-profile Republicans are stepping up to support his general election challenger — should Specter get through the Democratic primary — former Rep. Pat Toomey (R).

Former Virginia Rep. Tom Davis (R), who is now at Ernst & Young, American Council of Life Insurers President Frank Keating, former Republican Party Chairman Jim Nicholson and his wife, Suzanne, were among the powerful Washingtonians listed as hosting a fundraiser for Toomey at the end of February.

National Republican Senatorial Committee Chairman John Cornyn (Texas) also attended the $1,000-per-couple reception at the home of Phillip and Patricia Norton.

A cabal of former Republican aides-turned-lobbyists also banded together Tuesday for a young professionals event for Toomey, with Republican Sens. John Thune (S.D.) and John Barrasso (Wyo.) as special guests. Peck, Madigan, Jones & Stewart’s Drew Cantor, a one-time aide to former Sen. Rick Santorum (R-Pa.); Cesar Conda of Navigators Global; Mathew Lapinski of Sonnenschein Nath & Rosenthal; and Nickles Group lobbyist Brian Wild, a former Toomey chief of staff, were among those listed as co-hosts for the low-dollar event. Attendees were asked to contribute $50 for individuals.

Business groups have also taken a second look at supporting Specter.

Several associations that had been lobbying Specter to vote against the Employee Free Choice Act, which is a top priority of organized labor, met after his decision to switch parties. The groups opted to “keep their powder dry” until they knew how he was going to vote on the “card check” bill, according to lobbyists familiar with the discussions.

But the hold on contributing to Toomey was canceled after Specter came out in support of card check.

Specter says he isn’t worried about defections.

“My colleagues and former aides have been very supportive,” Specter said. “There was only one person on my staff, the Senate staff, who did not feel comfortable staying on, but stayed on for several weeks until I found a replacement.”

“People who have been loyal to me in the past have been very loyal, and I’ve been very loyal to them. That’s a two-way street,” he added.

Still, Specter’s decision to relinquish the GOP moniker has left many Republican power brokers unwilling to write him a check.

Many Republicans wanted to support Toomey in 2004, when he challenged Specter in the GOP primary, but felt they couldn’t because there was pressure from party leaders to back Specter, according to several lobbyists.

Additionally, for Republicans looking to potential future careers in government service, writing a check to a Democrat doesn’t look good.

Still, after 30 years in office, Specter’s K Street tentacles are far-reaching. His former aides include Craig Snyder of IKON Public Affairs, David Urban of American Continental Group, Jennifer Castagna of Washington Partners and Bill Morley of Altrius Group. James Twaddell of Drinker Biddle & Reath, Dan Renberg of Arent Fox and Michael Tetuan of Prism Public Affairs are also former Specter staffers.

Specter’s stable of former aides on K Street remains loyal.

Chief among them is Urban, a former chief of staff to Specter who remains close to the Pennsylvania Democrat.

“I’m continuing my support for Senator Specter because I believe his dedication and commitment to Pennsylvania are without equal,” Urban said. “He fights aggressively for his constituents back home and what he believes is in America’s best interest — changing the letter after his name hasn’t changed any of that.”

Urban has been a key member of Specter’s fundraising committee and is continuing to act in that capacity.

Morley, another longtime Specter aide, is also supporting him despite the party change.

“I think he made a decision he felt was necessary at the time — some people disagree with it, some agree with it,” Morley said. “I would have hoped that he would not have made that decision as a Republican and today he would be in a strong position electorally if he had stayed.”

A former legal counsel to Specter, Morley said that he isn’t asking for his political contribution back, but he hasn’t decided yet whether he’ll volunteer in the state this cycle.

While there has been little crossover between Specter’s and Toomey’s staffs, Aimee Steel of Holland & Knight had the rare opportunity of working in the communications office for both Pennsylvanians.

Steel said she enjoyed working for Specter directly out of college, but her politics are more in line with Toomey.

“I think that Pat’s support in 2004 and now stems from him being very principled in his conservative beliefs,” Steel said in an e-mail. “There is nothing knee-jerk about him; he studies policies and issues thoroughly before drawing conclusions.”

Shira Toeplitz contributed to this report.