The Senate has its rule in place against making personal attacks against each other on the floor for several years, and Massachusetts Sen. Elizabeth Warren shouldn't have been surprised when she was rebuked, former Sen. Rick Santorum said Wednesday.

"You can't refer to a senator directly by their name," Santorum, now a political commentator for CNN, told the "New Day" program, noting that he's also been shut down under the Senate rule.

"You have to refer to them as a gentle lady or gentleman from another state. The whole reason for the rules is to keep the temperature down and keep decorum and make it a deliberate body."

The rules are in place to avoid personal attacks and making direct accusations against another senator, said Santorum, and generally, sometimes you get a little heated on the floor, you directly address a senator and you call them out on something and then they say, 'You can't do that.'"

However, Warren refused to back down from her demand to read a letter written by Rev. Martin Luther King Jr.'s widow, Coretta Scott King, in 1986 in protest against confirmation hearings for Alabama Sen. Jeff Sessions, when he'd been nominated for a federal judge's seat.

Sessions, now President Donald Trump's nominee for attorney general is set for confirmation this week, despite opponents' concerns about racially charged statements he'd made in the past.

"In the case of Elizabeth Warren, she didn't back off," Santorum told CNN. "She made those comments, she said she agreed with those comments and she suffered the consequences."

Tuesday night's event, meanwhile, have become a "rallying cry" for Democrats, said Santorum, "as Democrats across the country are more energized and excited."

Meanwhile, Democrats are "picking a wrong fight" when it comes to opposing and boycotting Trump's cabinet picks, said Santorum.

"I served during the Clinton administration, but I don't recall doing that, and the reason I didn't is because the president wins the election, and he can put his own people in place," said Santorum.

"You may not agree with the policies of the president but you don't obstruct qualified people to do the job that the president is set out to do. You pick your fights."