California Gov. Gavin Newsom's executive order mandating a vote-by-mail election in November is unconstitutional and must be stopped, Republican congressional candidate.Darrell Issa asserted Saturday.

Issa, appearing on "Fox & Friends Weekend," said he and a conservative group are challenging the Democratic governor over the directive because it could lead to possible manipulation of the vote.

"The Legislature passed an act specifically laying out how mail-in ballots could be done county by county. The governor ignored all of that, and ignored other ways he could have increased the amount of mail-in ballots," he said.

Issa accused Newsom of opening up polling places in an unsuccessful 11th-hour attempt to thwart the recent election of Republican Mike Garcia in the 25th District, which was supposed to be a mail-in ballot contest.

DARRELL ISSA, JUDICIAL WATCH CHALLENGE NEWSOM'S VOTE-BY-MAIL ORDER

"So you can see where one gets very concerned that this has turned into the governor's way to manipulate the outcome of the November election," he contended.

Issa, a former congressman, is vying this year to return to the House to represent a San Diego-area district.  He and other plaintiffs, including the conservative group Judicial Watch, are asking a federal judge in Sacramento to block Newsom's order.

Newsom says his directive is on firm legal ground. He called the switch to mail-in ballots a necessary response to the COVID-19 pandemic since voters at crowded vote centers could be exposed if they voted in person.

Following an April 7 election in Wisconsin, the state's Department of Health reported that at least 67 residents had been infected with COVID-19 after voting in person or working at the polls. It was not clear how many infections had been caused by the spring election because some had other possible exposures.

California would be the first state to switch to vote by mail due to the pandemic.

Voters masked against coronavirus line up at Riverside High School for Wisconsin's primary election Tuesday April 7, 2020, in Milwaukee. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Morry Gash)

While Newsom's move won praise from his party's leaders last week, the Republican National Committee said it was also weighing its legal options.

On "Fox & Friends," Issa was asked if the order is on firm legal ground.

"Just the opposite," Issa replied. "California law very specifically didn't give him this authority and laid out another way to do it."

Issa argues that Newsom’s order is an “unlawful attempt to supersede and replace California election law” by creating “an entirely new system” that does not conform with the state's Voter’s Choice Act, which lays out requirements for counties wishing to mail ballots to all voters.

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Issa said Newsom's order lacks safeguards aimed at ensuring that mail-in  ballots "go out to people who still live, who still exist, who still are at the address where they registered maybe when they got their license four or five years ago."

"But he’s not doing that," he said. "There are no safeguards in the system, and it's pretty clear that come November he may play the same trick again of opening polling places in the middle of a pandemic because it suits him."