For those wondering: No, there will not be a limit. "We'll give out 20 rounds" if the president tweets 20 times, Ashley Saunders, the bar's general manager, said in an interview.
As she spoke, Ms. Saunders was testing a way to create a huge display of Mr. Trump's Twitter feed that would run alongside the live coverage on the bar's 18 television screens — the better for her Capitol Hill clientele to follow any presidential play-by-play.
"I wouldn't be surprised if people took half-days or take the day off," Ms. Saunders said. "If I had a normal job, I don't know what I'd be doing."
Broadcast networks rarely cut into lucrative morning programming for news events — especially for congressional testimony, typically a dry-as-sawdust slog of grandstanding lawmakers and nondescript witnesses. But the potential for scandalous revelations has a way of reeling in ratings.
The 1987 testimony of Lt. Col. Oliver L. North at the Iran-contra hearings lured nearly five times as many viewers as the era's most popular soap opera, "General Hospital." One network estimated at the time that as many as 55 million people watched all or part of the hearing. Justice Thomas's Supreme Court confirmation hearings, deemed R-rated for frank allegations of sexual harassment, drew bigger audiences than some of the competing baseball playoffs in 1991.
Discussing his network's decision to run special coverage of Mr. Comey's testimony, Ryan Kadro, a CBS News executive producer, said: "It was a no-brainer for us. Our affiliates want it, and we want it."
Not everyone at Jimmy's Ice House in Houston might agree.
A dive bar 1,400 miles away from the nation's capital, Jimmy's is popular with military veterans like Doug Samuels, a retired Navy officer who voted for Mr. Trump. Nursing a Bud Light on Wednesday, Mr. Samuels said he was unlikely to watch the Comey broadcast live.
"I'd rather just listen to the pundits discuss it afterward," he said, a display of pro-Trump bumper stickers on a nearby table's legs.
"The thing with Comey is he wanted to make himself famous," Mr. Samuels said. "I don't think he's going to have anything new to say."
He added: "It's a diversion so that Democrats can keep attention off the things that really need looking into."
If Mr. Samuels decides to tune in, he will have the option: The Jimmy's bartender, Leah Bradley, said the bar would probably show the hearing live.
Mr. Comey's appearance before Congress in March, when he still had his job, was the last time the broadcast networks broke in for a live congressional hearing. Mr. Kadro said CBS planned to carry much of Mr. Comey's testimony, including his questioning by senators.
If Mr. Trump tweets, the CBS team — anchored in New York by John Dickerson, Gayle King, Norah O'Donnell and Charlie Rose — will be ready. The crew has rehearsed scenarios to ensure that viewers can be notified of any presidential retorts as they happen. "We're going to be covering the way the event is reverberating out to Washington and to the world," Mr. Kadro said.
In Gaithersburg, Md., Joshua Schuman said he planned to lead a discussion about the testimony in his 10th-grade government class at Quince Orchard High School. For the past few weeks, his students have been asking about the latest headlines on their iPhones concerning the F.B.I. director's coming testimony.
All the Comey questions were cutting into class time.
"I've warned them that it could be incredibly anti-climactic," Mr. Schuman wrote in an email on Wednesday. "But most of them are pretty intrigued by the fact that the president seems to have possibly broken the law."
Mr. Schuman is preparing to talk about highlights from the hearing, with an eye toward just how unusual the situation has become.
"I've really been emphasizing that this isn't 'business as usual' in Washington," Mr. Schuman wrote. "It's more like a real-life political thriller — 'Game of Thrones,' playing out down the street."