While most Democrats are likely reveling in Texas Gov. Rick Perry’s sliding poll numbers in the GOP presidential primary campaign, at least one is wishing him well.

Rep. Henry Cuellar (D-Texas) said that if his home-state governor wins the GOP nomination, he would refuse to campaign against him.

Perry’s candidacy puts Cuellar, a member of the House Democratic leadership, in an awkward spot, wedged between party allegiance and loyalty to a friend.

As a result, he will sit on the sidelines should Perry clinch the nomination to run against President Barack Obama; neither his party nor his friend can count on his active participation on their behalf.

“I am torn a little bit,” said Cuellar, who served as Perry’s first secretary of state. “I will not campaign against Perry, I will say that up front. It’s a personal thing with Perry. When it comes to the elections, I’m voting Democratic. But certainly, at the same time, he is a friend of mine.”

The relationship goes back to the 1980s, when the men served in the Texas Legislature — or as Cuellar put it, “I knew him when he was a Democrat.”

Perry served as a Democrat from 1984 until he switched parties in 1989. He served two more years as a Republican before becoming state agriculture commissioner and then lieutenant governor. Cuellar served in the Legislature from 1987 to 2001.

When then-Gov. George W. Bush resigned in December 2000 to become president, Perry took over as governor, and in his first appointment the next year, he named Cuellar secretary of state.

The bipartisan appointment was not unheard of for the era in Texas politics from which the men emerged, said Bill Ratliff, who was Perry’s lieutenant governor when Cuellar was secretary of state.

“Back in the days that we served, it wouldn’t have been an unusual situation,” he said. “Governors usually put their friends in there, but it’s not an influential office.”

In that position, though, Cuellar said he did influence at least one decision that has come back to haunt Perry’s presidential ambitions.

Perry was considering a bill that would allow illegal immigrants to have driver’s licenses and another that would allow children of illegal immigrants to receive in-state tuition at Texas universities.

“I told him to veto the driver license legislation, and he vetoed it, and I told him to sign the tuition bill, which I think was the right thing to do,” Cuellar said.

Now that Perry’s support for the Texas version of the DREAM Act has caused him to get booed by audiences at two separate presidential debates, “I feel a little bit responsible,” Cuellar said. “When you see a friend of yours go through this situation, you feel for him. He’s been slumping a little bit, but it’s still a long time before the Republican primary is over.”

Cuellar’s relationship with Perry, however, was not always pristine. Cuellar abruptly resigned after six months as secretary of state, discontent with Perry’s choice not to let him appoint his own deputy, according to news reports at the time.

“At the end of Cuellar’s tenure, the relationship wasn’t particularly warm,” state Rep. Pete Gallego (D), who entered the state House the year Perry left, said in an interview. “I don’t think they were particularly close.”

Perry campaign spokesman Ray Sullivan said the relationship was never “very social” but called Cuellar “a Democrat we can on occasion work with to benefit our state as a whole.”

“Their relationship was built on mutual respect forged in the [state] Capitol on policy and what’s best for Texas,” said Sullivan, who worked in Perry’s administration. “He has a history of supporting Texans who run for the White House. He’s done it in the past regardless of party. He recognizes that it would be good for the delegation on both sides of the aisle and for our state to have a Texan in the White House.”

Indeed, in 2000, Cuellar endorsed Bush over then-Vice President Al Gore. Although he has not endorsed Perry in gubernatorial races, he has held back from endorsing his opponents, most recently former Houston Mayor Bill White (D) in 2010.

Cuellar’s interests haven’t always entirely aligned with those of his party either.

During his first term in Congress, Cuellar voted against the majority of his party nearly a third of the time. He has since come into the fold, however, voting with his party about 90 percent of the time in his past three terms. In the 112th Congress, he was named vice chairman of the Democratic Steering and Policy Committee.

Earlier this month, Cuellar became the only Democrat to vote against a resolution by Rep. Jesse Jackson Jr. (D-Ill.) criticizing Perry for using a hunting camp named “Niggerhead.” The resolution did not pass.

“I did that because, listen, I know Rick Perry, and he’s no racist,” Cuellar said. “If you’re going to literally get up there and call someone a racist, you need to take a little time and look at the facts.”

Cuellar has not always been so loyal to his boosters, though.

He won his seat in Congress against an incumbent Democrat, then-Rep. Ciro Rodrigez, even though Rodriguez backed Cuellar’s first failed bid for Congress against then-Rep. Henry Bonilla (R) two years earlier.

Despite his leadership role, Cuellar’s refusal to campaign against Perry is not likely to be met with repercussions in the House should Perry win the GOP nomination.

“There is no requirement to campaign against the GOP candidate,” a senior Democratic aide said.

Correction: Oct. 20, 2011

An earlier version of this story misstated the number of times that Rep. Henry Cuellar (D-Texas) had run against against incumbent Democrats. Cuellar ran once against an incumbent Democrat.