GOP Rep. Devin Nunes may be Public Enemy No. 1 for Democrats nationally, but in his Central Valley hometown of Tulare, he’s easing his way toward a new term in office.

As chairman of the House Intelligence Committee, Nunes is the man behind a disputed memo released Friday that suggested leaders of the FBI and Justice Department abused their powers to wiretap an adviser to Donald Trump’s 2016 presidential campaign.

Nunes’ successful effort to declassify and release the Republican staff-written memo prompted Democratic leaders Rep. Nancy Pelosi of San Francisco and Sen. Chuck Schumer of New York to call for him to be removed as head of the committee.

Activist group Common Cause accused Nunes of leading a “gross politicization of a grave national security matter for partisan gain.” Credo, a progressive activist group, has started a petition to remove Nunes from the committee, saying his independence from President Trump has been compromised. And Democrats have him on their growing list of California congressional targets for November.

But it would take a partisan tsunami of unprecedented proportions this fall to oust the 44-year-old Nunes from the seat he was first elected to in 2002.

The dispute over the intelligence memo “won’t have any effect,” said Rep. Jared Huffman, D-San Rafael. “He’s alienated every Democrat within 1,000 miles of his district, and he’ll still be re-elected.”

Nunes’ district includes much of Fresno and Tulare counties, as well as part of the city of Fresno and all of Tulare, Clovis (Fresno County) and Visalia (Tulare County). Republicans hold a 43 percent to 33 percent registration advantage, and Nunes was re-elected in 2016 with better than two-thirds of the vote.

The Democratic Congressional Campaign Committee added Nunes to its target list in May, after he was forced to recuse himself — at least temporarily — from his committee’s investigation into Russian meddling in the 2016 presidential election because of questionable dealings with the Trump White House.

The Democrats’ seven top GOP targets in California, however, are all in districts that Hillary Clinton won in 2016. Trump won Nunes’ district, 52 percent to 43 percent.

“I don’t see (the intelligence memo) as being something Nunes can’t explain to his constituents in a way that satisfies them,” said Nathan Monroe, a political science professor at UC Merced. If the Republican registration advantage were two percentage points instead of 10, he added, “then there might be something to worry about.”

The southern Central Valley has become one of the most reliably Republican parts of the state, and the increasing partisan flavor of the national political debate makes it tougher than ever to oust entrenched incumbents, Republicans and Democrats alike.

“Voters out there aren’t evaluating candidates over and over, checking to see if they still agree with their views,” Monroe said. “Now a huge part of the electorate is saying, ‘I’m a Republican and he’s a Republican, so we’re on the same team.’ And the same with Democrats.”

Central Valley Republicans on the Democrats’ hit list, such as Reps. Jeff Denham of Turlock (Stanislaus County) and David Valadao of Hanford (Kings County), represent districts where the GOP registration advantage is less lopsided, forcing them to downplay their support of Trump.

Nunes, in contrast, has been able to join House Majority Leader Kevin McCarthy, who represents a neighboring district that includes Bakersfield, in full-throated backing of the president in his growing war with the nation’s intelligence apparatus.

“It’s clear that top (FBI and Justice Department) officials used unverified information in a court document to fuel a counter-intelligence investigation during an American political campaign,” Nunes said in a statement Wednesday.

That’s probably good enough for many voters in Nunes’ district, Monroe said.

“There are enough questions being raised by Republicans about the investigation,” he said. “There’s plenty out there for people who want to support him to hold onto.”

That doesn’t mean that Nunes hasn’t paid attention to the nuts and bolts — and dollars — of his re-election bid. His campaign finance statement released this week showed that on Dec. 31, Nunes had $3.8 million in the bank. His Democratic challengers, Andrew Janz and Bobby Bliatout, had a mere $84,647 and $59,979, respectively.

“Democrats haven’t done a thing to indicate they’re competing for this seat except putting Nunes’ name on a D.C. hit list,” Jack Pandol of the National Republican Congressional Committee said in an email. “Central Valley voters know Congressman Nunes is a crusader for more water and good-paying jobs.”

But a long shot isn’t the same as no shot, and Democrats in Nunes’ district keep working in the hope that something might happen between now and Nov. 6 that will put the seat in play.

Janz, 33, is a deputy district attorney for Fresno County who is making his first run for elective office. His campaign team knows it’s an uphill battle, but there are signs for encouragement.

“We’re definitely feeling the change” since the talk of Nunes’ memo hit the national news, said Heather Greven, Janz’s campaign manager. “We’re hearing from Democrats, independents and Republicans unhappy with Nunes. In the past seven days, we’ve raised about $100,000 in online donations.”

A recent poll suggested that 61 percent of independent voters in the district are willing to vote for a Democrat, she said, although that doesn’t cut into Nunes’ GOP support.

That doesn’t matter, Greven said.

“This is the first time (Nunes) has had a real challenge,” she said. “My goal is to make him spend every dime of his money in the bank.”

John Wildermuth is a San Francisco Chronicle staff writer. Email: jwildermuth@sfchronicle.com Twitter: @jfwildermuth