After Democrats won control of the White House and bolstered their numbers on the Hill in November, I've asked many Republican lobbyists how their business might be affected.

Most have replied to me that Democrats did not have a filibuster-proof majority in the Senate, which meant that clients still needed help from Republicans on K Street if they expected to defeat or pass legislation.

Well, that marketing pitch to clients likely got a whole lot weaker after today's bombshell news that Sen. Arlen Specter, R-Pa., was switching parties to join the Democratic caucus. If the still-unsettled Senate race in Minnesota results in Democrat Al Franken as the winner, as expected, the Democrats will have a filibuster-proof majority. That's likely to mean K Street Republicans are going to have to tailor their pitches.

John Feehery, a Republican lobbyist and founder of the Feehery Group, thinks business and advocacy groups who want to stop legislation in Congress are going to have to turn to grassroots and public relations strategies to have an impact.

"It will require popular outrage to stop things as opposed to inside Washington deals," he said. "To slow things down will require a lot more [popular] heat being put on Democrat moderates and Blue Dogs."

Cesar Conda, a Republican and co-founder of the bipartisan firm Navigators Global, makes the argument that Specter isn't necessarily going to be a reliable vote for Democrats and that means Republicans on K Street still have clout.

"He's not going to be a rubber stamp for cloture," Conda said.

Indeed Specter told reporters Tuesday afternoon: "I will not be changing my own personal independence nor my own approach to individual issues. I will not be an automatic 60th vote."

And while labor leaders expressed enthusiasm that Specter's switch means renewed life for the union-organizing "card-check" bill, the Pennsylvania senator said he is still opposed. "I think it is a bad bill, and I'm opposed to it," he said. "I would not vote to invoke cloture."

Of course this is all good news from Democratic lobbyists on K Street, who will be in more demand than ever.

Readers meanwhile, do you have any thoughts? What do our Republican readers On K Street think? Email me.
                                                  --Bara Vaida (with reporting by Hotline's Jennifer Skalka)