Sen. Marsha Blackburn (R-Tenn.) said she read a book during the third day of proceedings of President Trump's impeachment trial in the upper chamber on Thursday.

"First - I'm reading Resistance (At All Costs) by Kim Strassel. Read the chapter on obstruction. It provides good insights into today's proceedings," she tweeted Thursday afternoon.

"Second - busy mamas are the best at multi-tasking. Try it," she continued.

Her comments came in response to another tweet shared by conservative columnist Jennifer Rubin, who is a contributor for The Washington Post, calling reports of Blackburn's actions "shameful."

"@MarshaBlackburn might improve her understanding of the facts and law if she paid attention. This is shameful," Rubin tweeted.

Under the rules of decorum laid out for senators ahead of the impeachment trial, senators are only permitted to have reading materials if they "pertain to the matter before the Senate."

During the trial, which bars senators from bringing their phones or electronic devices into the chamber, Sen. Richard Burr (R-N.C.) also handed out fidget spinners to his colleagues while hosting a lunch for Republican senators.

According to CNN, Sen. Rand Paul (R-Ky.) also spent some time doodling a picture of the Capitol during the trial on Thursday.