(AP) – In California’s Central Valley, the nation’s great fruit-and-nut basket, voters like Lou Waller could help determine which party controls the U.S. House.

The 76-year-old retiree is an independent, the fastest-growing political affiliation in California. They make up nearly a quarter of voters in the 10th Congressional District, which has been flooded with campaign cash as Republican Rep. Jeff Denham tries to stop Democrat Josh Harder from taking his job.

Harder has pulled in over $6 million and Denham $4.5 million. At least 26 outside groups have spent another $10 million trying to influence the race, according to California Target Book, which analyzes campaigns.

The region known for producing cherries, grapes and almonds has long been sundered by political fights over water policy and immigration, but this year it’s another issue that convinced Waller to support the incumbent.

“It all stems from the Kavanaugh hearing,” Waller said outside a grocery. He’s punishing Democrats with his vote, outraged over what he saw as unfair treatment of Supreme Court Justice Brett Kavanaugh by Senate Democrats during confirmation hearings.

“I’ve got a bitter taste in my mouth about the whole situation,” Waller said.

Fallout from the Kavanaugh hearings is mixing with divisions over health care, President Donald Trump and immigration reform to create a neck-and-neck race in the district 80 miles (129 kilometers) east of San Francisco where Democrats count a slender registration edge and whites and Hispanics make up nearly equal parts of the population.

It’s one of a string of Republican-held districts in California carried by Hillary Clinton in the 2016 presidential election that Democrats have targeted to pick up the 23 seats they need to win House control.

Last week, as several dozen Harder campaign volunteers prepared to knock on doors, he told them Trump’s election helped prompt his run. He said on election night 2016 he and his wife were devastated after planning a party with champagne to toast an expected Democratic victory.

“I made a commitment that night to make sure that I felt differently two years later – been working on that every single day since then,” Harder said. Voters are looking for a check against Trump policies that have “made things worse for most people in this community,” he said.

Anna Roberts, 61, was among the volunteers. The self-described moderate Democrat pointed to Denham’s voting record on health care as a main reason she supports Harder. She worries Republicans will try to privatize Medicare and she’ll see her costs rise.

“I’m interested in senior issues because I’m becoming a senior,” she said. “My private health care costs have skyrocketed.”

The two candidates strike a contrast in backgrounds and style.

The 51-year-old congressman leases land to a nut orchard; Harder is a 32-year-old venture capitalist.

Denham voted to repeal the Affordable Care Act, while Harder supports it. Denham, an Air Force veteran, backs the president while Harder says Republicans in Washington are not doing enough to help an area with high poverty.

Denham, a former legislator first elected to the House in 2010, has been a perennial target for Democrats. But the congressman, known for his involvement in water issues vital to agriculture, has proven tough to beat. He won by 3 percentage points in 2016.

Central Valley politics are different from those in contested House seats in Southern California, which run through suburban tracts where college-educated, Republican women have been deserting Trump.

Among farm-belt Republicans, as with conservative states around the country, “there is no hesitation to support the president’s agenda,” Republican pollster Mike Madrid said.

Another crucial issue will be turnout by Hispanics. Democrats need a big showing from the group that trends Democratic but are historically inconsistent voters. Denham will look to cut into the Hispanic vote, too, to keep the Democratic margin down.

Denham has pushed for Congress to consider a pathway for citizenship for hundreds of thousands of immigrants who came to the U.S. as children and stayed here illegally.

The high stakes were underscored last week when Denham supporters circulated voting records that appeared to show Harder illegally voted in two locations in the 2016 election. The records were legitimate but there was a misinterpretation that the document from Stanislaus County showed Harder voted there when he actually only voted in San Francisco.

Harder said the incident shows the Denham campaign is “desperate to talk about anything other than Denham’s votes in Congress over the last two years.”

Denham attributed the close race to money pouring in from outside the district to support Harder – he calls his rival a San Francisco Bay Area outsider.

“When this kind of money comes in from the Bay Area and the amount of money that’s on TV, there’s certainly a lot of distractions for people,” he said.

Denham pointed to his support from organizations that represent farms in the district and highlighted his work with local veteran groups.

“This is a local campaign,” he said. “This is the fifth time they’ve moved somebody into this district to run against me.”

Harder’s campaign argues that he’s every bit the local product as Denham. He grew up in Turlock, which is in the district, moved away for college and graduate school, lived in San Francisco for seven months in 2016, then came back.

In the final days before the election, Harder says his campaign is focused on talking to voters about the Republican-backed health care and immigration policies thst Denham has supported in Congress, including his votes against the Affordable Care Act.