Trump-linked firm helped ignite 'Stop the Steal' protest outside Philadelphia vote-counting station
President Donald Trump at a campaign rally during the House of Representatives impeachment vote. (Max Elram /

A Republican firm run by a Trump campaign aide helped send text messages encouraging the president's supporters to show up outside the Philadelphia Convention Center, where election officials counted votes inside.

The messages came from phone numbers leased by Opn Sesame, which provides texting services for GOP candidates and causes, a source familiar with the operation told the Washington Post.

“ALERT: Radical Liberals & Dems are trying to steal this election from Trump!" read the message, which was sent hours before Joe Biden claimed a lead in the state. “We need YOU! Show your support at the corner of 12th St. & Arch St. in Philadelphia.”

Opn Sesame is run by Gary Coby, the digital director of President Donald Trump's re-election campaign, although it's not clear which of his clients ordered the message promoting the "Stop the Steal" protests.

The text messages sent Thursday do not mention the company, the president or his campaign, and were first flagged by the call-blocking smartphone app RoboKiller.

Trump, his two eldest sons and other campaign allies have suggested fraud and impropriety in the vote counts in states where mail-in ballots have eroded or erased his Election Day preliminary leads.

Some of Trump's supporters have protested outside buildings where votes are being counted, variously calling for a halt or continuation depending on the president's position there.