Donald Trump. Pool/Getty Images A top Democratic senator told Business Insider on Monday that Sen. Chuck Grassley, the Republican chairman of the Senate Judiciary Committee, is unlikely to be swayed in his handling of the committee's Russia-related work by anything President Donald Trump tweets.

Sen. Chris Coons of Delaware, a member of the Judiciary Committee, was responding to a Sunday Trump tweet that some saw as veiled message to Grassley, who spent the weekend explaining his decisions related to planned testimony from Donald Trump Jr. and former Trump campaign chairman Paul Manafort.

"It's very sad that Republicans, even some that were carried over the line on my back, do very little to protect their President," Trump wrote Sunday.

Grassley, an Iowa senator, and Senate Intelligence Chairman Richard Burr of North Carolina are the two Republican senators faced with leading high-profile Russia probes. Both were up for reelection in 2016, and both outperformed Trump at the ballot box.

"Look, President Trump tweets all sorts of things," Coons said. "Some of them make sense, many of them do not."

"My expectation is that Chairman Grassley will continue to do his job as the chairman and will pay less attention to social media than he will the traditions of the Senate and to executing his responsibilities faithfully," he continued.

Originally set for a public hearing, Manafort and Trump Jr. are now both set to soon testify to the committee behind closed doors. While they will not be under oath during the testimony, Grassley tweeted this weekend that it is "a crime to lie to Congress" regardless.

"On record intrvw w my & Sen Feinstein staff for hrs is no walk in the park," Grassley tweeted Monday. "Can be tougher than few minutes w members in hrg."