A record 19.7 million Californians are registered to vote in Tuesday’s election, a number that shows just how important these midterm contests are to people in the state, Secretary of State Alex Padilla said Friday.

“It’s almost unprecedented to set a registration record in a midterm election,” because far more people typically vote when a presidential race is on the ballot, Padilla said at a news conference in San Francisco. “Californians are fired up and ready to vote this year.”

The number of registered voters is about 1.9 million more than in the 2014 midterm election. Registered voters represent 78.1 percent of the 25.2 million Californians eligible to vote, which is also a record.

Padilla declined to predict Tuesday’s turnout, but noted that vote-by-mail ballots are surging.

“I think we’re going to have a very good turnout,” he said. “People are paying attention to politics right now.”

Padilla, joined by Attorney General Xavier Becerra, was talking up the state’s Voter Bill of Rights, a list of what citizens can expect when they cast their ballots.

Speaking alternately in English and Spanish, Padilla reminded voters that if they are in line by the time polls close at 8 p.m. Tuesday, election workers must stay until they cast their ballot. He also said people have the right to take up to two hours off from their jobs to vote, without loss of pay, providing they give their employers two working days’ notice.

Padilla also warned that in the past, social media sites have provided false information about voting and voting rights. The state’s VoteSure site is designed to answer most voters’ questions, he said.

Becerra said a team of state Justice Department attorneys will be spread across the state, “ready and available to protect that (voting) right, even if it means taking a fast dash to the courts.”

That hasn’t happened in years, he added, mainly because California “has done a lot to remove the impediments to voting that exist elsewhere.”

Although the polls close at 8 p.m. Tuesday, the election will linger for days or weeks, Padilla said.

By law, counties must count every mail ballot that is postmarked by election day and arrives by Friday. Voters also have eight days to fix problems with signatures on their mailed or provisional ballots.

Matching signatures to registration cards takes time, as does processing late-arriving mailed ballots. If a vote is close, a hand count of the ballots may be required.

“It can take several weeks to get the final, final results,” Padilla said. The state has until Dec. 14 to certify the election.

A handful of California congressional races may determine whether Republicans or Democrats control the House for the next two years, so the entire nation could be watching the state’s extended vote count.

No one will be watching more closely than House Democratic leader Nancy Pelosi of San Francisco, who could regain the speakership she surrendered to the GOP nearly eight years ago if her party nets 23 House seats. On Friday she made a brief stop at Laborers Local 261 in the Mission District, joining local and state Democrats in a get-out-the-vote event for volunteers.

Pelosi said she was confident Democrats will flip the House, but she declined to predict the margin of victory.

“I think we will win,” she said. “I don’t know what the number will be beyond that. If one looks at the races, one could say that we could easily reach 30. But we’ll see.”

John Wildermuth is a San Francisco Chronicle staff writer. Email: jwildermuth@sfchronicle.com Twitter: @jfwildermuth