SACRAMENTO, Calif. (AP) — Control of the U.S. House may come down to results in California, where a seemingly drawn-out process of counting votes has left the balance of power in Washington in limbo.

More than a week after Election Day, and with Republicans just one seat shy of winning the chamber, seven of the 10 House races The Associated Press has yet to call are in the Golden State, though one is between two Democrats. In some of the races, ballots are coming in at a trickle.

Placer County in the 3rd Congressional District, for example, reports that it has more than 105,000 outstanding ballots. The county added just 490 votes to its totals in the district Tuesday, and it doesn't expect to report results again until Friday.

California's lengthy count may be frustrating to candidates and anxious voters looking for certainty on who will control the House. But election officials say the process is designed to make it as easy as possible for people to vote and ensure every ballot is accurately counted.

“We have a huge population of registered voters and California stresses enfranchisement, so we have a process that by law ensures both voting rights and the integrity of elections,” Secretary of State Shirley Weber said in a statement this week. “I would call on all everyone to be patient.”

California has 21 million registered voters, more than any other state, and one of the nation's most expansive vote-by-mail policies.

As of Wednesday afternoon, more than 8.5 million ballots had been processed in California — more than have been counted in either Texas or Florida, the nation's second- and third-most populous states.

Weber's office estimates that about 2.3 million remain to be tallied, most of them mail-in ballots.

People who voted by mail had a choice of sending their ballots back or dropping them off at a vote center. Ballots postmarked by Election Day are counted as long as they arrive at county election offices within seven days.

In Texas, by comparison, mail ballots must be postmarked by Election Day and received by election officials by the following day.

Processing mail ballots is a lot more complicated than simply feeding them through a counting machine. The tallying itself is often fast — it’s the work that must happen ahead of time that takes a while, said Donna Johnson, the former president of the California Association of Clerks and Elections Officials.

The signature on each ballot must be matched with what's on file for the voter, a process that can be done manually or by machine. People whose signatures don't match have a chance to prove it is their ballot, a process known as “curing" that takes additional time.

Ballots also need to be taken out of their envelopes before they can be tallied.

Many California counties don't update their vote counts every day. Johnson said that's because election workers in some places will spend an entire day on verifying signatures on a massive batch of ballots, the following day on extracting them from the envelopes and the one after that on the actual count.

Counties have 30 days to finish.

“At the end of the day, we know that every ballot that can be counted is counted and the process is accurate,” Johnson said.

More money and better equipment could potentially speed things up. But that wouldn't change the deadlines that elections offices have to complete their work.

Many counties hire temporary workers to help, and some have to rent out warehouses or large office spaces to handle the large number of ballots, Johnson said.

Voters could also help the process move faster — mail ballots can be counted starting 29 days before Election Day, but many people wait until the last minute to turn theirs in.

Kim Alexander of the California Voter Foundation, a nonprofit that advocates for equal access to voting and more funding for elections, said the state could do more outreach to people about getting their ballots in sooner, and providing more early in-person voting opportunities could also help.

California's large number of voters and congressional districts, plus all of the options for casting ballots, can lead to more waiting than in other states, Alexander said.

“It’s a trade-off,” she said. “I think people have learned to be patient and that this is something we’re learning to live with. But I do think that we're also going to keep looking for ways to improve the process.”