National Democrats hope disapproval of President Donald Trump will help flip nine of California’s 14 Republican-held congressional seats, but campaign finance reports show Republican incumbents will make it expensive for them.

Six of them raised at least $750,000 during the first half of 2017, the San Francisco Chronicle reported. While Democratic challengers have raised less so far, they’ll get help from the party and outside groups past the primaries.

One of the Democrats vying to take on Republican Rep. Ed Royce has already put $2 million of his own money into his campaign. In his campaign launch video, insurance executive Andy Thorburn said he is willing to use his own wealth to support his campaign.

Thorburn is joined in the Democratic primary race by pediatrician Mai-Khanh Tran, who brought in $273,000, and former college professor Phil Janowicz, who raised $180,000.

Royce, who has represented the Orange County seat since 1992, had $3.1 million in the bank heading into 2017. Since January he has added $959,000.

The other five who raised more than $750,000 are: Reps. Mimi Walters, Jeff Denham, Darrell Issa, Devin Nunes, and David Valadao. 

While Royce was re-elected with 57 percent of the vote in 2016, Hillary Clinton’s win in Orange County has given Democrats hope for 2018. Clinton was the first Democrat since the Great Depression to carry the county, home of Republican President Richard Nixon.

Royce does have the incumbent advantage on his side, as do the rest of the targeted Republican congressmen. The University of Virginia’s Center for Politics found that House incumbents had a 97 percent success rate in the 2016 elections. Out of the 393 representatives who sought re-election, only 13 total lost in either the primary or general election.

That doesn’t mean Republican incumbents are safe. Democrats hold every statewide office in California and are determined to increase their majority of the 53 congressional representatives.

The Democratic Congressional Campaign Committee announced in April that it was moving senior Washington staffers to Orange County to organize election efforts in California and other western states. This is the first time the DCCC has had a full-time staffer stationed in the West since the 2000 election.

But national Republicans know the targeted GOP incumbents are vulnerable. National Republican Congressional Committee has made clear it knows certain California Republicans are vulnerable. Four of the 20 Republican incumbents on the National Republican Congressional Committee’s Patriot Program are from California.

Denham, Issa, Valadao and Rep. Steve Knight are all on the list. The Patriot Program includes incumbents that face tough re-election battles.

Issa beat Democrat Doug Applegate by about 1,600 votes in 2016. Since January he has raised $813,000, adding to the already $671,000 in his campaign chest.

Applegate is already preparing for a rematch, raising $384,000 so far in 2017, with $262,000 in the bank. The retired Marine colonel will first have to face off against Democratic activist Mike Levin, who has brought in $615,000 during the first half of this year.

Meanwhile, outside groups in California are also preparing for expensive 2018 elections. The conservative Congressional Leadership Fund has focused on 12 vulnerable Republican districts to work in, four of which are in California. The PAC plans to spend $1 million in each district.