Democrats could gain 40 House seats as GOP Rep. falls behind in California

If that lead holds, Democrats will not only win a seventh U.S. House seat from the GOP in California, but it would give Democrats a net gain of 40 seats nationwide.

And that would also translate into an unprecedented partisan advantage in California, with 46 Democrats and just 7 Republicans from the largest Congressional delegation in the nation.

Valadao's seat had been a target for Democrats simply because it was one of 25 different districts which voted for Hillary Clinton in 2016, but elected a Republican lawmaker to the U.S. House at the same time.

In 2016, Clinton won this district by over 15 percent - but on Election Night in 2018, Valadao seemed to have avoided defeat, as he led Cox by 5,000 votes, with a margin of close to eight percent - so, the race was called for the GOP by the Associated Press and the major news networks.

But as the counting continued, that vote advantage for Republicans kept slipping, and was finally erased on Monday.

The race is not over - as more outstanding ballots must be tallied in several counties, with the most in Fresno County.

For now, election experts in Washington believe that Cox has the edge - but that won't be known for certain until at least December 7, when counties in California must certify their election results.

"In case there was any doubt on election night, it is now clear — this is what a wave looks like," said Rep. Adam Schiff (D-CA).

The extended vote count in California is normal, as the state takes its time to count millions of vote-by-mail, absentee, and provisional ballots - though, to many outsiders it might go on too long.

"Mississippi is going to conduct and count and entirely new election before California is done with the first one," said elections expert Nathan Gonzales, referring to Tuesday's special election for U.S. Senate in the Magnolia State.

But when you compare the population of the two states - California at nearly 40 million people, to Mississippi at almost 3 million - the length of time it takes to conduct an election is more involved as well.