By SCOTT SONNER, Associated Press

RENO, Nev. (AP) — On the same day a Republican challenger jumped in the race against Sen. Dean Heller, dozens of mostly Democratic protesters rallied outside his Reno office to denounce his latest position on health care.

The attacks illustrate the political angst on both the right and the left that Heller will have to navigate to be re-elected next year in his role as arguably the most vulnerable incumbent Republican in the U.S.

Heller already has voted both ways on health care. He opposed two Trump-backed measures — one to replace the Obama-era law, the other to repeal and come up with a replacement in the future. He later backed a final stripped-down bill known as 'skinny repeal,' which also failed.

Tuesday's protesters — wearing "Heath Care Voter" t-shirts and buttons saying "I Stand With Planned Parenthood" — questioned Heller's principles and characterized him with words like "wishy washy."

"I don't like the way that he says one thing in private and doesn't tell the truth in public," said protester Fran Puchli, grasping a sign that said "2018 Unseat Dean Heller."

Las Vegas businessman Danny Tarkanian read from practically the same script — albeit from the opposite end of the political spectrum — in announcing his primary bid to unseat Heller.

Tarkanian said he's been inundated with texts, emails and phone calls from Nevadans upset with Heller "for campaigning one way in Nevada and voting the exact opposite in Washington D.C."

"The refrain is the same: He turned his back on us," said Tarkanian, 55, the son of University of Nevada, Las Vegas basketball coach Jerry Tarkanian.

Tarkanian's campaign makes good on conservatives' threats to challenge incumbents they blame for hurting their yearslong quest to dismantle the 2010 health care law. Tarkanian has been unapologetic in his support of President Donald Trump.

Heller was keeping a low profile during the August congressional recess and had no direct comment on the recent developments. His campaign spokesman Tommy Ferraro dismissed Tarkanian as a "perennial candidate" who has never won a major race, "wasted conservatives' time and cost the Republican Party seats up and down the ballot."

The last time both political parties were so closely watching Heller's every move, he was refereeing another high-stakes U.S. Senate battle two decades ago.

As Nevada's secretary of state, he was responsible for formally certifying Democratic Sen. Harry Reid's 1998 re-election victory by just 428 votes after a monthlong recount.

Despite a legal challenge and pressure from GOP leaders to do anything he could to derail what would become Reid's ascension to Senate majority leader, Heller insisted he had to follow the law and certify the vote in accordance with state election rules.

With some exceptions, his impartiality drew high praise and earned him respect from the old guard in both parties.

"He deserves a medal for bipartisanship," Reid said at the time. "They were trying to push him into being partisan and he refused to be partisan."

The political drama came at a time when Nevada's status as a Republican stronghold was shifting. GOP presidential candidates failed to carry the state only once from 1952 to 1988 before Democrat Bill Clinton won in 1992 and 1996.

The state went Republican for George Bush the next two times, but Barack Obama won twice, followed by Hillary Clinton in November, making Heller the only Republican seeking re-election in 2018 in a state that rejected Trump.

Heller has increasingly drawn the ire of Democrats who had viewed him as an acceptably moderate Republican but watched him gravitate, in their eyes, more to the right.

He won some back when he refused to endorse Trump for president, spoke out against the president's travel ban this year and at one point sided with Nevada GOP Gov. Brian Sandoval in criticizing the impact Trump's health care cuts would have on Medicaid.

But Heller has voted both ways since. And while the attacks from the left long were anticipated, the Republican infighting may prove more problematic.

That will include fending off Tarkanian, who most recently lost a congressional race in November to Democrat Jacky Rosen.

"I really feel sorry for Dean. He's trying to present some sort of unified approach when you have a party that is at war with itself," said Randi Thompson, a longtime Republican consultant in Reno.

Rosen announced last month she's seeking Heller's Senate seat.

The month before, a political advocacy group run by an ex-White House aide and Trump campaign veterans ran television advertisements targeting Heller after he surprised members of his own party with a press conference denouncing the GOP's Senate health care plan to repeal and replace the Obama health law.

The group backed off under pressure from Senate Majority Leader Mitch McConnell. And the National Republican Senatorial Committee run by McConnell immediately expressed its support for Heller following Tarkanian's announcement on Tuesday.

"Time and again, Senator Dean Heller has proven he is unafraid to put Nevadans first," NRSC spokesman Michael McAdams said.

Thompson said Heller is probably more concerned about surviving the primary than winning the general election in November.

"It's going to be a tough race for him no doubt," she said. "I just hope he remembers who got him there. It was the Republicans. It was the people who want him to repeal and replace 'Obamacare.'"