Republican megadonor and Las Vegas Sands CEO Sheldon Adelson and his wife, Miriam, gave the Senate's GOP fundraising arm over $200,000 last month as the party works to protect its majority in the chamber during next year's elections.

Their massive donations came in July, with each writing checks worth $106,500 to the National Republican Senatorial Committee, according to a new Federal Election Commission disclosure filed Tuesday.

The early contribution may reflect that the GOP donor class are concerned about the upcoming 2020 elections, with political analysts already labeling at least three seats as toss-ups. The GOP will defend 22 Senate seats next year. The party has a 53-47 edge in the Senate.

The NRSC finished July raising $4.3 million and has $11.7 million on hand.

Republican strategists, however, tried to brush off the donation as only a sign of the Adelsons being consistent, big-dollar supporters.

"Very consistent supporters," Josh Holmes, a former chief of staff to Senate Majority Leader Mitch McConnell, told CNBC. "I think it reflects their continued support of Senate Republicans. Not sure I can make any more of it than that."

The Adelsons had been relatively quiet so far in the current election cycle. They've given directly to a variety of candidates, but this six figure donation would mark their highest contribution so far.

The two combined to give over $120 million to Republican causes throughout the 2018 congressional midterm cycle.