The highest-profile lawsuit of Alexander Kolodin’s career was supposed to be a doozy, one of a suite of legal filings that were meant to “release the kraken” and prove that the 2020 election had been rigged in favor of Joseph R. Biden Jr.

Instead, a federal judge in Phoenix, Diane Humetewa, dismissed the case, finding claims of sea monster-sized voter fraud to be “sorely wanting of relevant or reliable evidence.” The filing’s 300-plus pages of attachments, she said, were “only impressive for their volume.” The Arizona State Bar later fined Mr. Kolodin, sent him to mandatory ethics classes and placed him on probation for violating his “duty to the legal profession, the legal system and the public.”

On Tuesday, Arizona Republican primary voters nominated Mr. Kolodin to be their candidate for secretary of state, the top election official in the key political battleground.

Mr. Kolodin’s victory alarmed Democrats, and some Republicans, who see him as a hard-driving election denier who would restrict access to voting and would go along with the election conspiracy theories pushed by President Trump and his administration. Mr. Kolodin, an Ivy League-educated lawyer who is in the State Legislature’s far-right Freedom Caucus, has said that Democrats are the ones who have undermined confidence in Arizona’s elections.

Both sides of the Kolodin divide see the race as vital since Arizona could decide which party controls Congress and possibly the Oval Office.

“The secretary of state is the most important chief elections officer in the world,” Mr. Kolodin said on a conservative podcast this month, “because the road to the White House runs directly through that office; the road to the congressional majority runs directly through that office.”

Adrian Fontes, the Democrat currently serving as secretary of state, has already begun highlighting Mr. Kolodin’s record, including his unfounded claims of “massive election fraud” in 2020 and his legal work on behalf of the Cyber Ninjas, the firm that oversaw a chaotic audit of that race and failed to turn up any evidence that Mr. Trump was cheated of victory.

Mr. Kolodin and his campaign did not respond to repeated requests for comment.

Mr. Kolodin’s race against Gina Swoboda, a former chairwoman of the Arizona Republican Party, wasn’t all that close; he beat her by about 20 percentage points. But in the famously divided Arizona Republican Party, his echoing of Mr. Trump’s false claims could alienate the moderates and independents who often decide general elections.

“He’s trying to scare voters who are concerned about election integrity into thinking the system is terribly broken and that he’s going to fix it,” said Ken Bennett, a Republican former secretary of state. “I think he’s going to make it worse. And if he’s going to lie about that stuff, I don’t want him anywhere near that office.”

This year, Mr. Kolodin successfully spearheaded an effort to place a measure on the November ballot that, if approved by voters, would order up a range of changes that Democrats, as well as some Republicans and local elections officials, say would make casting and counting ballots more difficult.

Its provisions include a requirement that Arizonans must show valid proof of ID when voting by mail — the state’s most popular way of casting ballots — but it does not explain how voters would do that. State law already requires residents to show ID when they register to vote, and elections officials verify the signatures of all mailed ballots. Ms. Swoboda, a former aid to the secretary of state, said the proposal would “crush” mail voting.

The measure would also allow voters to have their ballots tabulated at their voting location rather a central counting site, a change that some local election officials say would require counties to purchase dozens of new machines and could introduce security risks.

The Arizona Association of Counties, which represents those officials, opposes the move, but with Mr. Kolodin campaigning for it and himself, the initiative could draw outsize attention this fall.

Mr. Kolodin has lately sought to avoid discussing his role in the 2020 lawsuit. He has said he understands that mail-in voting is popular and promised that “nobody is coming to take that away.” Instead, he framed his ballot measure as an attempt to secure the process.

After his primary win, Mr. Kolodin invoked the grand Republican senators of Arizona’s past, John McCain and Barry Goldwater, figureheads of a bygone political era.

“Whether you’re a McCain independent, a Trump Republican, or a Goldwater Democrat, I want you to know that our campaign is about protecting every vote,” Mr. Kolodin said.

The top elections official in Maricopa County, Justin Heap, who served with Mr. Kolodin in the Statehouse Freedom Caucus, called the nominee a meticulous legislator and “one of Arizona’s foremost authorities on election law.”

“Alex wasn’t someone who relied on talking points or partisan grandstanding; he did the work,” Mr. Heap said. “He knew the statutes, the case law, the history behind the legislation and the practical implications of every proposal we considered.”

Mr. Heap, who has sparred with fellow Maricopa County Republicans over elections duties, credited Mr. Kolodin for “many of Arizona’s most consequential bipartisan election reforms” and said he would be responsive to the concerns of county elections officials.

In his three and a half years in the State Legislature, Mr. Kolodin has cultivated a contrarian reputation, which last year earned him the Best Political Jester award from The Phoenix New Times, the city’s alternative newspaper.

He has pushed to repeal the state’s ban on machine guns and pipe bombs and supported executions by firing squad. He was the sole vote against a measure outlawing lying about military service.

That stance received a fiery response from the bill’s sponsor, State Representative Walt Blackman, a Republican who has criticized Mr. Kolodin’s wing of the party for stoking “infighting and extremism.” But after Mr. Kolodin’s primary win, Mr. Blackman seemed to lean into party unity, commending the nominee for being “practical and really serious about the Constitution.”

“You should go into that office and leave your political ideology at the door,” Mr. Blackman said of the secretary of state post. “I think he’s capable of doing that.”

Mr. Kolodin also teamed up with Democrats on a bill to protect people who are wrongly prosecuted.

Mr. Fontes, who has sparred with Mr. Kolodin in court, said after the primary that his opponent “has spent years attacking Arizona’s elections and spreading lies about our democracy.”

In her campaign for secretary of state, Ms. Swoboda’s central argument was that Mr. Kolodin was destined to lose to Mr. Fontes, who defeated another far-right challenger, Mark Finchem, in 2022. In a televised debate, Ms. Swoboda warned that Mr. Kolodin’s censure from the state bar would be a liability in November.

Mr. Kolodin scoffed. “The voters of this state,” he said, “are tired of hearing about 2020.”