Nevada Gov. Steve Sisolak at a February event in Las Vegas. Photo: Alex Wong/Getty Images

Nevada Gov. Steve Sisolak (D) announced Monday evening that he's signed a bill enabling all registered voters in the state to vote by mail in November's elections.

Why it matters: President Trump told reporters Monday he'd sue Nevada in a bid to stop the mail-in measure. After Sisolak's announcement, Trump retweeted his earlier tweet stating: "In an illegal late night coup, Nevada's clubhouse Governor made it impossible for Republicans to win the state. Post Office could never handle the Traffic of Mail-In Votes without preparation. Using Covid to steal the state. See you in Court!"

Go deeper: Trump stokes fears of election-night mail voting fraud

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Christopher Wray: FBI has not seen evidence of national voter fraud effort by mail

FBI Director Christopher Wray responded to a question on the security of mail-in voting to the Senate Homeland Security Committee on Thursday by saying that the agency has "not seen, historically, any kind of coordinated national voter fraud effort in a major election, whether it's by mail or otherwise."

Why it matters: President Trump has ramped up his claims, without evidence, that widespread mail-in voting would rig the 2020 election against him. On Wednesday, after declining to say whether he would commit to a peaceful transition of power if he loses the election to Joe Biden, Trump said that "the ballots are out of control."

Updated Sep 25, 2020 - Politics & Policy

Pennsylvania's "naked ballots" are 2020's hanging chads

A stack of mail-in ballot applications in Pennsylvania. Photo: Ben Hasty/MediaNews Group/Reading Eagle via Getty Images

Pennsylvania's Supreme Court ordered state officials last week to throw out mail-in ballots submitted without a required inner "secrecy" envelope in November's election, the Philadelphia Inquirer reports.

The state of play: The decision went under the radar alongside the simultaneous decision to extend the time that mail-in ballots could be counted, but Philadelphia's top elections official warned state legislators this week that throwing out so-called "naked ballots" could bring "electoral chaos" to the state and cause "tens of thousands of votes" to be thrown out — potentially tipping the presidential election.

Sanders: "This is an election between Donald Trump and democracy"

Photo: BernieSanders.com

In an urgent appeal on Thursday, Sen. Bernie Sanders (I-Vt.) said President Trump presented "unique threats to our democracy" and detailed a plan to ensure the election results will be honored and that voters can cast their ballots safely.

Driving the news: When asked yesterday whether he would commit to a peaceful transfer of power if he loses, Trump would not, and said: "We're going to have to see what happens."