LOS ANGELES - For all their talk of a "blue wave," Democrats needed a good day Tuesday in California to have much hope of seizing the House majority this fall.

No state will play a more significant role in the fight for control of Congress. And with primary elections across California and seven other states on Tuesday, the political battlefield will soon be set for the first midterm elections of Donald Trump's presidency.

The first waves of polls closed Tuesday evening in New Jersey, Alabama, Mississippi, South Dakota and New Mexico.

Mississippi Republican Senator Roger Wicker won his primary contest as did New Jersey Senator Bob Menendez, a Democrat who faced federal bribery charges last year. The jury deadlocked, but Republicans hope to use Menendez's legal troubles to tar other Democrats across the state, including those fighting to defeat vulnerable GOP incumbents in suburban districts.

Meanwhile, the Democrats got their favored nominees in two key New Jersey congressional races. Democrat Mikie Sherrill, a former federal prosecutor and Navy pilot, and state Senator Jeff Van Drew emerged Democratic winners in races to replace two retiring Republicans. Both House seats are viewed as prime pickup opportunities for the Democrats.

Meanwhile, two women sought the GOP nominations in governors' races. In Alabama, Governor Kay Ivey faced three GOP challengers, and in South Dakota Representative Kristi Noem hoped to become the state GOP's first female nominee for governor.

California's results, however, may not be finalized for days in some cases because the state will count any mail ballots postmarked by Tuesday.

Recognizing the high stakes, Trump sought to energize his supporters in a series of tweets praising his preferred California Republican candidates.

"In High Tax, High Crime California, be sure to get out and vote for Republican John Cox for Governor. He will make a BIG difference!" Trump tweeted.

Yet nightmare scenarios exist for both parties.

Because of California's unusual primary system, Trump's party faces the embarrassing prospect of not qualifying any candidate for the governor's race or the Senate. Democrats, meanwhile, could be shut out of a handful of competitive House races because they ran too many primary candidates and diluted their vote.

It Mississippi, 66-year-old Gladys Cruz wasn't sure which Republican she would support in the state's Senate primary, but she wants whoever wins to firmly support Trump.

The president "touches my heart," she said.

California will be the most consequential state in the fight for congressional control, featuring seven Republican seats in districts won by Democratic presidential nominee Hillary Clinton in 2016.

Yet the state's unusual election laws complicate things for both sides.. All candidates appear on a single primary ballot, with the top two vote-getters regardless of party advancing to the November election. That allows the possibility of two candidates from the same party qualifying.

AP