As the Senate weighs the impeachment of a president for only the third time in U.S. history, the usually decorum-filled chamber at times has been more akin to a high school classroom.

There was gum-chewing, snacking and yawning.

U.S. Sen. Rand Paul even reportedly worked on a crossword puzzle and crafted a paper airplane as House managers made their case Wednesday for removing President Donald Trump, whom the Kentucky senator has backed vehemently.

In what U.S. Supreme Court Chief Justice John Roberts called the "world’s greatest deliberative body," senators from both sides of the aisle took liberties with the rules.

Sen. Mark Warner, D-Va., could be seen at his desk in the back row, leaning on his right arm with a hand covering his eyes — remaining in that position for nearly 30 minutes. Sen. Elizabeth Warren of Massachusetts — a leading Democratic presidential candidate — played a game on paper, according to ABC.

Other senators were seen reading non-impeachment materials and emails. Some senators openly snickered when lead prosecutor Adam Schiff said he’d only speak for 10 minutes. And when one of the freshman House prosecutors stood to speak, many of the senators bolted for the cloak rooms, where their phones are stored.

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“I do see the members moving and taking a break,” observed freshman Rep. Jason Crow of Colorado, one of the House prosecutors, midspeech at the center podium. “I probably have another 15 minutes.”

The Senate has specific rules for impeachment trials. These include no coffee or snacking on the floor, no pacing, no working on other matters and no passing notes or chitchats.

The rules are in place to keep senators focused on the serious matter at hand. But with the trial's long hours, the House managers and president's legal team struggled to keep the jury's attention as evidenced by Paul's work on a crossword and paper airplane.

A Paul spokesman told ABC News, which first reported on the Republican's behavior, that "all smart people do crossword puzzles" when asked for comment Wednesday. His office did not respond to a phone call or email from The Courier Journal seeking comment Thursday.

Paul told The Washington Post this week that 45 Republican senators are willing to dismiss the case now.

Roberts, who is presiding over the trial, gaveled Tuesday's session closed at 1:50 a.m. Fewer than 12 hours later on Wednesday, the senators were back, with little sleep, for more of the same impeachment story. Warner and others had already started their day at a 10 a.m. Senate Intelligence Committee hearing.

Well into Schiff's second hour of opening arguments during the trial, he moved on from discussing the first of two charges against Trump.

"Now let me turn to the second article," he said. That prompted several senators to shift in their seats and smile at one another in apparent bemusement. It also sparked a small exodus for the cloakroom, especially on the Republican side, including Sen. Roy Blunt of Missouri and Sen. Tom Cotton of Arkansas.

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Crow, an Army veteran speaking on the impact of Trump's holdup of military aid to Ukraine, also had trouble holding the Senate's attention. Some senators headed to cloakrooms, stood in the back or openly yawned. At one point during his address, more than 10 senators' seats were empty.

Crow wondered aloud if the Senate wanted to take a recess.

No dice. Senate Majority Leader Mitch McConnell of Kentucky said there would be no break until dinner, more than an hour later.

Around midnight, things got looser. Senators paced and chatted near the wall. Then the prosecutors and Trump's defense team got into a back-and-forth over who was lying and making false allegations about Trump's pressure on Ukraine to help him politically.

Roberts admonished everyone to tone it down. The Senate, he reminded those gathered, has a tradition of civility.

The water-only practice seemed to be one guideline the senators could get around by tradition.

Cotton, for example, was seen drinking a glass of milk early in the day. Spokeswoman Caroline Tabler said Cotton was drinking skim milk — a complement to the chocolate snacks he and other senators were getting in their cloakroom and from one lawmaker's desk.

Like so much about the fusty Senate, even the beverage exceptions are rooted in history. Sen. Bill Cassidy, R-La., told reporters that milk joined water as the only officially permitted drinks in the Senate chamber in the 1950s. Cassidy, a doctor, said that at the time, milk was believed to be a treatment for stomach ulcers.

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According to the Senate Historical Office, Sen. Robert LaFollette, R-Wis., drank eggnog during a 1908 filibuster, and Sen. Strom Thurmond of South Carolina, while still a Democrat in 1957, drank orange juice during his record 24-hour filibuster against the Civil Rights Act.

Factoids aside, the novelty of the impeachment trial had clearly worn off. Senators had heard the Trump-Ukraine story before, many times. Their boredom, one Republican senator suggested, had become a challenge to the prolific House managers' strategy. Sen. Mike Rounds, a South Dakota Republican, said the less wordy president's legal team had “read the Senate” better.

“It was a long day and the House managers did a lot of repeating the same material," Rounds told reporters. "I’ve got 20 pages of notes, and towards the end, we were basically hearing the same thing over again. It was a diatribe.”

The Associated Press contributed to this report.

Reach breaking news reporter Sarah Ladd at sladd@courier-journal.com. Follow her on Twitter at @ladd_sarah. Support strong local journalism by subscribing today: courier-journal.com/subscribe.