Former San Jose Mayor Sam Liccardo has already secured his spot in the primary election to move ahead to the general.
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But just a handful of votes separate Evan Low and Joe Simitian who have been battling it out for the second candidate spot.
As of Tuesday evening, Simitian holds a five-vote lead on Low.
This congressional district encompasses both Santa Clara and San Mateo counties.
Tuesday was the last chance voters with ballots that needed to be fixed had a chance to correct them.
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That means after weeks of fluctuating results, all of the ballots that can be counted will be counted, leading to the final count expected Thursday.
The primary elections happened March 5 but the results of the race have been far from final.
March 12 was the last day county election offices would receive ballots sent by March 5 on primary election day.
Now April 2 at 5 p.m. was the next important deadline.
"The last day to cure any ballots that were out there that weren't signed or the signatures didn't match," said Evelyn Mendez, a spokesperson with the Office of the Santa Clara County Registrar.
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Election officials say voters have had weeks to fix or "cure" their ballots.
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"We send them multiple letters, emails, texts, however we can get a hold of the voter so we could tell them why their ballot isn't counted yet," Mendez said. "They can come in and cure it. That's what the ballot process is, where they can come fix it or sign something saying, 'Yes, this is my signature.'"
In Santa Clara County, many people have taken officials up on the offer.
In total, there were nearly 1,500 challenged ballots that needed to be fixed. In the last report before Tuesday's deadline, there were around 500.
San Mateo County reported just over 400 before the deadline.
Each vote is significant as it could be the final ones that decide who Liccardo's opponent will be.
At one point Low and Simitian were separated by as few as two votes but until the April 2 deadline, numbers were still changing as ballots were being cured and processed.
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Simitian sent ABC7 News a statement Tuesday that said:
"Sometimes it takes a while for democracy to work. This is one of those times. That means counting and verifying all of the votes. Every single one of them. The election offices in both counties have been verifying voter signatures over the past few weeks to make sure that every vote that can be counted, will be counted. Right now we're waiting to hear from them."
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Low's team said they will make a statement after the counties certify the election.
The counties will issue final results on April 4th.
After that, the Secretary of State will then certify the results on April 12.
Now in the final stretch of counting, election officials say the race serves an important reminder.
"We like to say every single vote counts," Mendez said, "We want to make sure that every voter knows they make a difference in every election."
Following the final election results and certification, either candidate can request a recount. The candidate making the request would have to pay for the recount, if it goes in their favor they would be refunded the money.