Easing voting laws enacted to allow Californians to cast their ballots in a variety of ways -- to the point that any friend or stranger can drop off a ballot for other voters -- has coincided with a rising Democratic tide sweeping through once solidly red swaths of the state in the last two elections.

But in a surprise twist, election officials in one heavily Democratic county east of San Francisco have fought for three years to fix a serious procedural flaw in the Golden State’s voting system: Voters can cast two ballots.

It’s not just a hypothetical. There’s documented proof that more than a hundred voters cast at least two ballots in Contra Costa County -- and at least 75 others double-voted in a nearby county -- in the 2016 primary, even though the loophole isn’t so widely known that voters are purposefully and systematically exploiting it, election officials say.

Extrapolating that 2016 experience across California, the largest state in the country by population, means thousands of voters likely voted twice in recent elections -- not that anyone would know because few other local and state officials were keeping track or really seemed to care, critics say.

The Contra Costa election officials who uncovered the problem and are focused on fixing it are growing increasingly frustrated by what they say is a lack of real concern in Sacramento about finding a solution that can be easily and consistently administered by the volunteers who work at polling places on Election Day.

Because Contra Costa County is so strongly Democratic – it’s congressmen are Reps. Eric Swalwell and Mark DeSaulnier — there’s no proof that the documented 113 voters casting two ballots in the 2016 election impacted the outcome of any federal race. However, the ability to vote twice could easily swing close intra-party campaigns for local office.

And with so many voter-fraud and other allegations hanging over California’s 2018 election, it’s a matter of preserving election integrity and closing a known loophole before it’s widely exploited, the officials say.

“It really isn’t a question of affecting outcomes, it’s just affecting the integrity of the process, and people’s views of the integrity,” Scott Konopasek, the Contra Costa assistant registrar of voters, told RealClearPolitics.

“People all around the country are saying there’s voter-fraud problems in California without real evidence that there’s been any abuse and misuse,” he continued. “And as election officials, we go out of our way to accommodate hypothetical concerns. And here we have a real, empirical, factual situation and the state is saying, ‘Nevermind.’ That concerns us. It’s inconsistent.”

The ability to vote twice in most of California’s 58 counties stems from the system that gives voters a choice of casting ballots by mail or at the polls on Election Day and the option to switch back and forth between the two. The problem is particularly acute during presidential primary elections, such as the one next year on March 3, which was moved up from June to give the state more influence in choosing a Democratic presidential nominee.

California mail-in ballots can be exchanged for ballots cast at polls.

Voters who decline to state a party preference and opt to vote by mail can later exchange their mail-in ballots for ballots from parties, including the Democratic Party, which allows crossover voting.

The loophole comes about quite naturally. When a voter’s nonpartisan primary ballot arrives in the mail, he or she may then realize they cannot participate in the Democratic primary unless they request a partisan Democratic ballot. After requesting one and receiving it, the voter can take the original nonpartisan ballot to a neighborhood polling location and exchange it for another Democratic ballot, which is also cast.

Election workers at the polls then have no way of knowing that the voter has already cast a ballot by mail. County officials at some point crosscheck the list of Election Day voters with those who mailed in ballots and determine whether some people voted twice. But by that time the ballots have already been commingled with all the others and counted – with no way to trace the second ballot cast by the same person.

Groups on the right, focused on ensuring that elections are secure and guarding against voter fraud, point to the loophole as another reason the rest of the country shouldn’t be taking election-innovation cues from California.

“We’re seeing a failure of leadership on the part of the [California] secretary of state to stomp out known vulnerabilities in the election system,” Logan Churchwell, a spokesman for the Public Interest Legal Foundation, a conservative law firm formed to bolster election integrity, told RealClearPolitics. “Anyone who raised alarm over foreign influence must take action against threats like corrupted registration records and compromised mail ballot systems. California has proven to fail on both counts.”

Churchwell was referring to the current double-voting flaw as well as California’s botched rollout last year of its new motor-voter registration system. A Los Angeles Times investigation showed that the latter, administered by an already strained DMV, was rushed into place by the state’s election officials before it was ready and was attacked by what appeared to be hackers in Croatia.

Kati Phillips, a spokeswoman for Common Cause, a nonpartisan organization that has praised California for providing greater access to the polls and more flexible voting options, said most of the state’s counties have systems in place to verify vote-by-mail ballots and cancel out or reject double votes.

“Plus, anyone who casts two ballots can be prosecuted,” she said.

Contra Costa election officials counter that most county election officials in California are not overly concerned about the loophole. Officials can only recommend prosecution if they take the time and effort in the post-election analysis to uncover if people voted twice, they add. What’s more, of the 113 double-voting cases they turned over to the local district attorney, only a handful were prosecuted.

The Contra Costa officials discovered this problem when a big push to increase vote-by-mail in the state coincided with the dramatic California Democratic presidential primary between Hillary Clinton and Bernie Sanders.

Joe Canciamilla, a former assemblyman who now serves as Contra County’s clerk-recorder and registrar of voters, said it’s a flaw not just in California but in other states whose elections operate in a similar way.

“We mail out ballots 29 to 30 days prior to an election and people aren’t always paying attention that early,” Canciamilla said. “They get a [nonpartisan] ballot that doesn’t have any presidential candidates on it, and they say, ‘Wait a minute, I want to vote in the presidential [primary].’ So they can request a Democratic ballot or they can go online and change the registration to Democrat and they can have a Democratic ballot sent to them.”

"The end result [of ballot exchanges] is we have all these ballots out there floating around." Joe Canciamilla, Contra Costa County registrar of voters

In testing that request system, Canciamilla said he and his fellow county election officials discovered that if voters request any change whatsoever to their voting registration record, such as a name change or address change or a legitimate request for a partisan ballot, they would be sent a new ballot.

“The end result is we have all these ballots out there floating around,” he said. “… When that’s the case, the whole idea of surrendering the ballot to vote no longer provides that security that was originally intended.”

Local media reports about the phenomenon have only heightened concerns and contributed to a lack of faith in the state’s election system. For example, before the 2018 midterm election, a local NBC news station reported that a San Diego County woman received four ballots in the mail, one addressed to her maiden name, one addressed to her married name, then a third sent to her married name and a fourth sent to her maiden name with a middle initial.

“If they can’t even manage to do this, then how can I trust them, as a citizen, to manage my tax money, or decide my health care?” she told the local station.

In Northern California, a man who reported getting three ballots checked with the Santa Clara County registrar of voters and was told he is only listed once on the voting rolls. Elsewhere, the Sacramento Bee reported that other voters had been receiving multiple ballots after signing up at the DMV for a Real ID, a new identification card required by the federal government to board domestic flights.

“If you asked them how many ballots they sent out, they’d say, ‘Only one,’” said the Santa Clara man who received three ballots. “They’re not on top of it completely at this point.”

To ensure that a voter can’t use the ballots to vote multiple times, Contra Costa officials proposed a simple solution: require voters who were issued two ballots to vote provisionally. In California, provisional ballots are designated as such and set aside to be counted later, when election officials can verify voters’ eligibility, including that the ballot signatures match those on file, and in this case to make sure the voters hadn’t already voted by mail or at another polling location on Election Day.

Provisional ballots are used to ensure that no properly registered voter is denied the right to vote if their name is not on the polling place roster because of a clerical, processing or other type of error.

The Contra Costa officials also proposed that voters could avoid casting a provisional ballot if they handed over all the ballots they received by mail and were willing to sign a declaration “under penalty of perjury” that they had “not previously voted and returned a ballot for this election that was issued to me.”

California Secretary of State Alex Padilla.

California Secretary of State Alex Padilla’s office rejected that method, arguing that state election law states that voters will be permitted to cast non-provisional ballots if they surrender their vote-by-mail ballots to poll workers on Election Day. Padilla’s lawyers interpreted this unconditional part of the law to mean that no extra sworn declaration that they had not previously voted was necessary.

In recent years, advocates on the left who support greater voting access and flexibility have taken issue with the use of provisional ballots, a system that requires voters to sign a form that takes time to fill out and for election officials to verify after Election Day.

In the 2016 Democratic primary, Sanders’ supporters also argued that their votes were already suppressed because the Associated Press called the outcome early in the day for Clinton. After Election Day, other reports of a different theory emerged – that millions of provisional ballots left uncounted on election night amounted to a Sanders victory over Clinton but were prevented from being added to the count.

Some of the reports cited the fact that 2.5 million early ballots and provisional ballots were not yet counted when the news networks called the primary as another reason to doubt that the race was fair to Sanders. They specifically cited evidence that voters with “no party preference” had difficulty casting regular and non-provisional ballots as contributing to the problem.

Two days later PolitiFact deemed the claim a “pants on fire viral rumor.” By that time, however, it was already lodged in the minds of Sanders’ supporters as a source of resentment and broadened a bias among the Democrats and some independents against the use of provisional ballots.

Phillips, the Common Cause spokesperson, said “provisional ballots are important because we don’t want folks being turned away from the polls, but they also are used as a last resort.”

Fast-forward to this summer and 2020 election preparations, and Contra Costa County is still squaring off with Padilla to find a way to close the double-voting loophole.

After Padilla’s office rejected the use of provisional ballots to solve it and ordered Contra Costa not to train poll workers to use that method, county officials have reluctantly followed those orders. But they are worried that the loophole will be further exploited in the coming primary and general elections.

“If you drill down, the real objection is one of perception – the perception of provisional ballots, and the state views it as an inferior method of voting and takes issue with the extra 30 to 45 seconds it takes to fill out the provisional ballot information,” said Canciamilla, the county elections chief. “They think a provisional ballot is somehow suppressing voters or giving them less of a vote. But there’s no evidence of that – it simply ensures the accuracy of the process.”

The perceived purpose of "provisional ballots has sort of changed from something that protects peoples’ rights to ... something that infringes their voting rights." Scott Konopasek, Contra Costa assistant registrar of voters

Konopasek said the provisional ballot concept is intended to enfranchise rather than disenfranchise when the eligibility of a specific voter cannot be determined.

“The whole idea of the purpose behind provisional ballots has sort of changed from something that protects peoples’ rights to being perceived as something that infringes their voting rights,” he said. “Maybe that’s because some states who have used it don’t count provisional ballots. But California and Western states don’t fall into that category.”

Padilla spokesman Sam Mahood said the issue is not really a matter for the secretary of state to decide, despite its role in rejecting Contra Costa County’s provisional ballot solution. Instead, Mahood put the onus on county elections officials “to issue and account for ballots” and cited “administrative means” that they can employ to mitigate and prevent double voting.

Asked to outline some of those administrative solutions, Mahood said county officials could consider suspending the processing of vote-by-mail ballots for voters who requested multiple ballots, segregating them for processing after Election Day when it could then be determined if the person tried to vote twice – once by mail and once in person.

“Another option would be to add a notation on the polling place roster that a voter was issued multiple vote-by-mail ballots,” he said. “If the voter cannot surrender both (or all) of the ballots that were issued to them at the polls, the county could require them to vote provisionally.”

Mahood added that “we stand ready to work with any county election office to implement administrative practices that protect the integrity of the election, preserve voting rights and follow state law.”

Contra Costa County officials reject those methods as overly costly and disruptive and involve more difficulty in training poll workers to ensure consistency and foolproof safeguards against voting twice.

“Our volunteers found these procedures difficult to consistently administer,” Konopasek said. “It was confusing. It was costly. It still did not eliminate the risk of someone voting twice. The more complex the process, the more stretched we get and the greater possibility there is for error.”

Daniel Borenstein, an award-winning columnist and editorial page editor with the Bay Area News Group, agrees. He took Padilla to task in a column last month for failing to lead on the issue and close the double-voting loophole in a simple, foolproof way.

“If there’s an administrative fix, he should have implemented it by now,” Borenstein wrote. “If there’s a legal problem, he has had three years to seek corrective legislation.

“If Padilla won’t lead on the issue, legislators and the governor should — and quickly,” he added. “The status quo of hundreds of people voting twice is unacceptable.”

Susan Crabtree is RealClearPolitics' White House/national political correspondent.