"This is maddening. It's maddeningly frustrating because this is beneath the dignity of the President of the United States, or at least it should be," the Pennsylvania senator said on CNN's "The Lead with Jake Tapper," adding, "It's a distraction. It starts to undermine his ability to get the agenda done."

Many other Republicans lawmakers expressed their frustration with the President's tweets attacking MSNBC co-hosts Joe Scarborough and Mika Brzezinski on Thursday, including Sens. Ben Sasse Tim Scott and several Republican members of the House.

Countless Democrats echoed similar sentiments across various platforms.

White House Deputy Press Secretary Sarah Huckabee Sanders defended the President's actions at a news conference Thursday afternoon.

"I think he's been very clear that, when attacked, he's going to hit back," Sanders said.

But Toomey said he'd rather see Trump spending his time on reworking Medicaid costs and finding solutions to the country's growing opioid crisis.

"We really need the President to focus on those things," Toomey said.

When Tapper noted that nearly 2.8 million Pennsylvanians are currently covered under Medicaid, Toomey asserted that none would be forced to give up their coverage under the American Health Care Act.

JUST WATCHED GOP lawmaker: Trump's tweets are concerning Replay More Videos ... MUST WATCH GOP lawmaker: Trump's tweets are concerning 01:27

"They won't lose coverage because of the Senate bill. We codify -- we make permanent -- Medicaid expansion," Toomey said.

Medicaid coverage would continue to increase under the GOP health care bill, but at a slower rate, according to Toomey, who asserted the bill would provide special funds for addiction treatment.

"I think having a shared responsibility for this cost between state and federal government -- as we do for everything else -- makes perfect sense," Toomey said.