Impeachment article has 200 cosponsors: US rep.

Republican former Maine Sen. Olympia Snowe has called on the president to resign following Wednesday's violent storming of the Capitol by a pro-Trump mob.

"President Trump should resign from office now to allow our nation to begin to heal and prepare for the transition to the Biden presidency," Snowe tweeted Saturday.

The former senator joins other Republicans, like Sen. Lisa Murkowski, R-Alaska, and Rep. Adam Kinzinger, R-Ill., in calling for the president to leave his post or for his removal before his term ends on Jan. 20.

Known as a moderate, Snowe served as senator from Maine between 1995 and 2013.

-ABC News' Benjamin Siegel

Federal law enforcement officials have advised police agencies in state capitals to increase their security posture at statehouses around the country following the riot at the US Capitol, law enforcement sources told ABC News.

The concern, the sources said, is an emboldened right-wing that considered Wednesday a success and may next turn to locations in closer to home.

Like the U.S. Capitol, statehouses are often backdrops for demonstrations that law enforcement officials now fear could turn violent.

“The safety of the Massachusetts State House, its employees and its neighbors is of utmost importance. As we witness the events in Washington, DC and across the nation, we are aware of the need to ensure the safety of this building and those who work within it. We continually assess our security needs and will adjust as necessary,” said Massachusetts Gov. Charlie Baker, Senate President Karen Spilka and House Speaker Ronald Mariano in a joint statement.

Across the country in Washington state, Gov. Jay Inslee activated the National Guard to patrol the Capitol Campus when the state legislature convenes Monday.

“As legislators begin their work on behalf of the people of the state of Washington, we must do whatever we can to ensure that they can do that work without fear, intimidation or harassment. The actions we saw in both Washington, D.C. and Olympia earlier this week were completely unacceptable and will not be repeated in our state capital again,” Inslee said.

Security was also increased around the statehouse in Maryland, Gov. Larry Hogan said.

“Maryland State Police as well as Maryland Capitol Police, some of which you see around here, have increased security around the Maryland State House complex, since there’s been a number of incidents at state capitols and governor’s mansions around the country,” Hogan said.

-ABC News' Aaron Katersky and Josh Margolin

Florida authorities say on Friday night they arrested one of the alleged Capitol rioters who was seen in a viral photograph carrying Speaker Nancy Pelosi’s lectern through the halls.

Adam Johnson, 36, of Parrish, Florida, is being held in Pinellas County Jail and charges are pending after federal marshals picked him up, according to arrest records.

Army Secretary Ryan McCarthy said Friday the Army will soon determine whether to allow Guardsmen to be armed for the inauguration based on a review of threat intelligence.

"We'll be looking at the intelligence and make a determination over the next day or so," McCarthy told the Associated Press. "It's just going to require us to get better intel, and then we'll have to make a risk assessment."

"The Secretary of the Army, in concert with Federal and Metropolitan leadership and D.C. National Guard continue to assess the security environment in the District of Columbia," an Army official told ABC News.

"As part of the standard mission analysis, we evaluate mission requirements based on requests, and it can include looking into the force posture level and the standing rules for the use of force. The Army is a planning organization and this a standard part of mission analysis," the official added.

- ABC News' Luis Martinez