Support for Congressional Republicans has gone to the dogs. And the cats, cows, chickens and horses.

In the latest sign that Republicans are consolidating their power in Washington, D.C., the Humane Society of the United States — the historically left-leaning lobby for all things furry — is now aggressively courting GOP lawmakers.

By showing the majority party that they don’t bite, the animal-welfare activists hope to have an easier time passing some of their biggest agenda items, including federal bans on animal fighting and horse slaughter, ending Internet hunting, and cracking down on mass dog-breeding facilities, called “puppy mills” by critics.

The sponsor of the dog-breeding legislation is Sen. Rick Santorum (R-Pa.), and in appreciation, the Humane Society has made his hotly contested re-election one of its top priorities. While most of the society’s usual allies on the left consider Santorum their No. 1 campaign target for 2006, Wayne Pacelle, the group’s president and CEO, is sticking to the strategy of reaching out to the GOP.

“There’s been a continuing recognition that we need Republicans to get these things done,” said Pacelle, who earlier in his career espoused a complete end to hunting everywhere.

At the helm of his organization, Pacelle has executed a dramatic turnaround.

Just four years ago, his group was giving 94 percent of its political action committee dollars to Democrats. So far this year, the society has steered $19,000, or 56 percent of its total giving, to Republicans, according to PoliticalMoneyLine.

The shift in political giving has accompanied a more pragmatic legislative approach. The group earlier this year hired Matt Keelen, a lobbyist with Valis Associates, to open the doors of skeptical Republicans on Capitol Hill.

“The benefit of having such popular issues is that you can really talk to anybody,” he said.

The switch of focus has not escaped the attention of gun and hunting groups, who are warily watching the Humane Society’s forays onto issues that they have historically owned in Washington.

“There are some very serious consequences to buying into what they are buying and selling,” said Bill Horn, lobbyist for the U.S. Sportsmen’s Alliance, a hunting group. “We’re always concerned when a group with a radical agenda is on the Hill making friends.”

Added Chris Cox, chief lobbyist for the National Rifle Association: “If Members of Congress work to advance the anti-gun and anti-hunting agenda of animal rights extremist groups like the Humane Society, we’ll take that into consideration when we make our endorsements.”

Keelen, himself a NRA member, said he sees his work as expanding his party’s tent. Tapping an extensive network of contacts in GOP circles he assembled during a decade of fundraising, Keelen has been reaching out to Republican lawmakers who had been largely unfamiliar with animal rights issues.

Keelen said he begins conversations by asking Members to support a cause that most would be hard-pressed to oppose: strengthening laws against the underground practice of animal fighting.

Though the practice is illegal in most states, dog- and cockfights pit animals, often drugged to heighten their aggressiveness, against each other in matches that can be fatal for both contenders. Gamecocks fight with razor-sharp steel blades attached to their legs, allowing them to break the legs and wings of their opponents, or gouge their eyes and slash their throats.

In dogfighting, canines are bred for aggressiveness and then trained to develop certain muscles, including jaws so strong they can break opponents’ legs.

“Animal fighting really shouldn’t be a partisan issue,” said Todd Mitchell, chief of staff to Rep. Rob Simmons (R-Conn.), who has worked closely with the Humane Society.

And if there was ever a time when animal causes rose above partisan tensions, it has been in the aftermath of Hurricane Katrina, which, according to Humane Society estimates, left 50,000 pets abandoned by displaced owners in New Orleans alone.

Pacelle has spent the days since the storm in the hardest-hit coastal areas, coordinating a massive recovery effort.

While the disaster has pushed the society’s resources to the brink, it’s had the unexpected effect of being a boon to its membership rolls, with 170,000 new members signing up since the storm hit.

As an early return on his group’s new investment in friendships with Republicans, Pacelle has two powerful GOP Senators making an appeal directly to the White House on behalf of the stranded animals.

Last Thursday, Republican Sens. Santorum and John Ensign (Nev.) sent a letter to President Bush urging him to appoint someone to coordinate pet rescue efforts.

“These animals represent not only an emotional concern but also a significant public health hazard,” they wrote.

Both Senators have long been outspoken defenders of animal rights. Ensign, a veterinarian by training, has campaigned for years to end the slaughter of horses for human consumption.

This week, the Senate will take up a bill he introduced to do just that — a move that won praise from no less than the editorial board of the conservative The Washington Times.

Santorum, for his part, is pushing legislation to crack down on puppy mills.

His home state is among the top 10 nationally for the facilities, which critics say are factories that mass-produce puppies without properly caring for them. Santorum, who owns a two-year old German Shepherd named Schatzie, recently introduced PAWS — the Pet Animal Welfare Statute — to regulate breeders who sell six or more litters a year.

“It’s an issue near and dear to his heart,” said his spokesman, Robert Traynham.

Despite working on animal issues for the better part of a decade, this is the first year either Ensign or Santorum has received campaign cash from the Humane Society.

“They will prove to be invaluable to the Senator’s re-election as it relates to spreading the message that he has been working hard on this issue for the last 10 years, and we’re very proud to be working with them,” Traynham said.

Kristina Wilfore, who heads the liberal Ballot Initiative Strategy Center, said the society’s pro-Republican shift is not well known yet in the liberal community. On the other hand, she said despite the common public perception, the Humane Society has often worked at arm’s length from such groups, including those pushing for minimum-wage hikes or abortion rights.

“Some animal rights folks are so myopically focused on their single-issue agenda they can’t see the political forest for the trees. It can be difficult to glean their long-term political strategy, which could obviously make it hard for them to understand the significance of switching teams. This move seems pretty opportunistic,” Wilfore said.

Pacelle explained the move as part of the group’s political maturation.

“You want to believe you’re above the cold, hard influence peddling in Washington. You want to believe you will win every argument on the merits,” he said. “But it doesn’t take a long stay in the city to recognize you’ve got to do more.”

Beyond their campaign donations, the society has an average of about 12,000 members in every Congressional district, providing it with considerable grass-roots muscle to aid its friends and challenge its foes.

Former Rep. Chris John (D-La.) learned that lesson the hard way. Hailing from one of the two states in the country where cockfighting is still legal, John once called the practice a “cultural, family-type thing” and blocked Congressional efforts to ban the sale of the birds across state lines.

The Humane Society remembered that when he announced his candidacy for the Senate last year. The group made his defeat its top political priority.

In the face of strong pressure from senior Democrats, Pacelle directed his group to spend $250,000 in the state to defeat John and elect Republican David Vitter. Vitter won, and Pacelle claims at least partial credit for that.

Louis Jacobson contributed to this report.