Democratic state Senate candidate Tom Umberg for the first time pulled ahead of state Sen. Janet Nguyen, R-Garden Grove, according to results released Monday by the Orange County Registrar of Voters.

Umberg leads Nguyen by 438 votes. He had been gaining steady ground on Nguyen since Election Night as mail-in and provisional ballots have been tallied.

There are about 6,500 ballots to still be counted in the Orange County portion of the 34th Senate District.

Umberg, a former federal prosecutor and Army veteran, served in the Assembly from 1990-94 and 2004-06.

Other races of note that have significantly tightened since Election Day include the contests for mayor in Anaheim and Santa Ana.

Santa Ana Mayor Miguel Pulido, who has been on the City Council since 1986 and the mayor since 1994, had a 50.9 percent-49.1 percent lead over Councilman Sal Tinajero. Pulido is leading by 904 votes.

Attorney Ashleigh Aitken trailed businessman Harry Sidhu by 1,400 votes as of Monday night. Sidhu declared victory Nov. 7, but Aitken has continued to gain ground.

Democratic congressional candidate Gil Cisneros, who held a pep rally to thank volunteers on Monday, extended his lead over Republican Young Kim in the 39th Congressional District.

According to the latest tallies released by election officials in Orange, Los Angeles and San Bernardino counties, Cisneros leads by 4,442 votes.

All of the congressional seats in Orange County will be occupied by Democrats. According to the Orange County Democratic Party it's the first time that has happened since 1940, when the county consisted of two congressional districts.

Cisneros will replace Kim's longtime boss, retiring Rep. Ed Royce, R-Brea.

Democrat Katie Porter has been declared the winner in her race against Rep. Mimi Walters, R-Irvine, who has conceded. Porter leads Walters 51.7 percent to 48.3 percent, according to the latest vote count.

Democrat Harley Rouda has a 53.3 percent to 46.8 percent lead over Rep. Dana Rohrabacher, R-Huntington Beach.

Democrat Cottie Petrie-Norris continued to build her lead over Republican Assemblyman Matthew Harper, 52.5 percent to 47.5 percent.

Fullerton Mayor Doug Chaffee, a Democrat, leads La Habra Mayor Tim Shaw, a Republican, by 572 votes in the nonpartisan race for the Fourth District seat on the Board of Supervisors.

Chaffee leads, 50.2 percent-49.8 percent.

There are about 80,000 more votes to tally with most of them being provisional and damaged ballots, according to Orange County Registrar Neal Kelley. Election officials expect about 20 percent of those votes could have come from unregistered voters and cannot be counted.