Liz Cheney abruptly ended her bid for the Senate Monday, but don't assume her campaign taught us anything about the state of the Republican Party. (The Washington Post)

Five months after shaking Wyoming Republican politics by launching an audacious bid to unseat the state’s senior senator, Liz Cheney on Monday called an abrupt end to her chaotic campaign, citing unspecified “serious health issues” that have arisen in her family.

The announcement by the ­eldest daughter of former vice president Richard B. Cheney caught her fellow Republicans by surprise, just as her decision to enter the race had in July.

Her campaign had not gained much political traction, but it had strained long-standing political loyalties in a state her father had represented in Congress for a decade and had exposed tensions among the Cheneys over the issue of same-sex marriage.

It also reflected some of the crosscurrents that are buffeting the Republican Party, where unexpected primary challenges from the right have antagonized red-state incumbents who were considered safe.

Her case, however, showed that there are limits to how well that kind of ambush can work. Not even the Cheney name — revered in Wyoming — was enough to overcome a host of problems that had beset her ­misstep-prone candidacy.

The campaign did not specify the nature of the health concerns.

The man Cheney was trying to unseat, Sen. Mike Enzi, said she called him Monday morning to say that she was dropping out and that a health issue with one of her five children prompted the sudden move.

“It was a brief conversation. And one of her children is having a health problem, so I hope everyone will keep them in their prayers,” Enzi told reporters after leaving the Senate floor following a vote.

Bill Scarlett, a family friend whose parents had chaired Cheney’s campaign, said: “I talked to her right before Christmas. We were at a family Christmas party, and I thought everything was full go.” He added: “It must be a serious issue for her to drop out. I mean, this family has been through heart attacks on the campaign trail.” Scarlett was referring to a famous incident from Dick Cheney’s first congressional race, in 1978.

All indications suggested that Liz Cheney was running far behind Enzi.

She had accused the affable lawmaker of being insufficiently conservative — even though he ranked further to the right than all but seven of his Senate colleagues, according to National Journal’s 2012 vote ratings. Cheney, 47, said she was part of a “new generation of leaders” — a comment that was considered a none-too-subtle way of suggesting that Enzi, 69, is past his prime.

But the biggest headlines Che­ney generated came in November, when a private disagreement between her and her sister, Mary Cheney, who is a lesbian, became a full-fledged public spat.

After Liz Cheney reiterated her opposition to same-sex marriage in an interview on “Fox News Sunday,” her sister — who married her longtime partner, Heather Poe, in 2012 — took to Facebook with a post that said, “Liz — this isn’t just an issue on which we disagree — you’re just wrong — and on the wrong side of history.”

Poe suggested that her sister-in-law is a hypocrite, noting in her own Facebook post that Liz Cheney “didn’t hesitate to tell us how happy she was for us” when the couple got married.

Dick Cheney and his wife, Lynne, issued a statement asserting that Liz Cheney had always opposed same-sex marriage and that her “many kindnesses shouldn’t be used to distort her position.”

Even without the drama she generated in her own family and the Wyoming Republican one, Cheney’s bid had been problematic.

She could trace her Wyoming roots back four generations, but she had spent most of her life in suburban Washington. A former State Department official and frequent television commentator, Cheney had long been considered a rising star, and some in the GOP hoped she might run for office in Virginia.

Instead, she moved to Wyoming in 2012, at a time when there was speculation that Enzi might not seek a fourth term.

He had not yet made his intentions known when Cheney posted a YouTube video announcing that she was running for his seat. The senator said of his opponent, “I thought we were friends.”

On Monday, Enzi said he and his wife respect Cheney’s decision.

“While it is not always easy, Diana and I have always believed in putting family first. We have tremendous respect for Liz’s decision. She and her entire family are in our thoughts and prayers,” he said.

In a state that measures its politicians by their authenticity, Cheney was criticized as a carpetbagger. She fueled that perception with blunders that included applying for a fishing license even though she had not lived in the state for the requisite year. More recently, it was revealed that Cheney’s husband, Phil Perry, had been registered to vote in both Virginia and Wyoming.

Still, her advisers insisted that Cheney had plenty of time to recover and gain ground before the August primary.

“There was an aggressive retail operation well underway in all 23 counties, which she has visited,” said Mary Matalin, a Cheney strategist. “She had in-state, stout leadership. She raised close to $2 million in the first two quarters. She had the right message about constitutional government and pushing back on Obama’s war on coal. It would have come together.”

Matalin said that Cheney will not hold on to that money for a future run. After paying all its bills, the campaign’s plan is to give back what is left, and it will start by returning contributions it received from small donors in Wyoming.

“I’m not saying there will never be any politics” in Cheney’s future, Matalin said. “But she’s got one priority here — getting the health of her family back to a stable position.”