Senate Majority Leader Mitch McConnell (R-Ky.) scolded Senate Republican colleagues on Thursday for skipping a Wednesday night vote, warning them that attendance needs to improve if anything is to get done in August, according to sources.

Congress usually takes the month of August off to meet with constituents around the country during what is known as a state work period.

But facing pressure from President Trump, McConnell canceled this year's August recess - to the chagrin of many of his colleagues.

McConnell warned fellow Republican senators at a private lunch meeting Thursday that he would have trouble moving legislation next week if the attendance remains as abysmal as it was this week.

He explained they were able to move business on the Senate floor yesterday and today only because they had locked in procedural agreements with Senate Minority Leader Charles Schumer (D-N.Y.) in advance.

Ten senators, almost all Republicans, missed two votes on Thursday.

That could be a big problem next week when McConnell tries to set up additional votes.

Eleven senators, again mostly Republicans, missed a vote that was scheduled for late Wednesday afternoon.

"He's rightfully, I think, upset. I wasn't at lunch but I knew what he was going to say," said Sen. John Thune (S.D.), chairman of the Senate Republican Conference.

Eight Republican senators, including Sen. John McCain (R-Ariz.), who is at home indefinitely battling cancer, missed Thursday's votes, effectively giving Democrats a majority in the chamber.

Only two Democrats, Sens. Dick Durbin (Ill.) and Patty Murray (Wash.), missed the votes.

One Republican who attended Thursday's lunch said the senators who were absent, not the ones who heard McConnell's stern speech, need to be chastised.

"He was preaching to the choir," the lawmaker said.

Another GOP senator said that most of his colleagues agreed about the importance of showing up for working during a time that is usually reserved for the August recess but some complained about it.

"He said, 'You got to show up,' " said the source, who added a couple of colleagues who have had to make long flights back to Washington said the unusual August session is a personal "hardship" for them.

Two Republican senators who didn't make it to Washington this week - Sens. Thom Tillis (N.C.) and Mike Lee (Utah) - signed a letter to McConnell in May urging him to cancel the August recess.

That raised the eyebrows of fellow Republicans who trekked to the nation's Capitol amid sweltering heat and humidity.

A spokesman for Lee said his boss "will be in D.C. to vote on appropriations bills next week."

Democrats mocked Republicans for making a big deal about canceling the August recess and then not showing up for votes.

"Feels a little bit like something that was done for optics rather than for substance. This is called political posturing - I recognize it. I'm in the middle of a campaign," said Sen. Claire McCaskill (D-Mo.).

Sen. Brian Schatz (D-Hawaii) said, "I'm always happy to do the work, but this is a little goofy."

Updated at 4:03 p.m.