WASHINGTON — While House Intelligence Committee chairman Adam Schiff is accusing President Donald Trump of a "shakedown" and raising the specter of impeachment, his counterpart in the Senate, Mark Warner, has yet to publicly opine on Trump's conduct during and surrounding the July telephone call with the Ukrainian president. The Twitter account of Warner, a Virginia Democrat, has been silent on the issue, and his remarks to reporters Thursday were subdued.

Two sources close to the committee say that's because he wants to keep Republican committee chairman Richard Burr of North Carolina on board with conducting what a Burr spokeswoman would only call an "inquiry" — not an investigation.

The Senate Intelligence Committee heard from the intelligence community inspector general and the director of national intelligence behind closed doors Thursday, and afterward Burr and Warner told reporters they would continue calling witnesses on the matter. But neither of them spoke to the question of whether Trump did anything wrong — a notable bit of restraint by Warner, as Democrats all around him are pouncing.

"One of the most important things that came out of today though was maintaining the integrity of the whistleblower process. People need to be able to come forward when they've seen instances of waste, fraud, abuse or inappropriate behavior," Warner said.

This starkly different approach by Warner speaks to the much different dynamic in the GOP-controlled Senate on this issue, as many Republicans dodge and defend Trump. Burr, who has announced he will retire when his term expires in 2023, took a lot of flack on the right by running a bipartisan Russia investigation, the fruits of which are to be made public over the next few weeks.

Burr and Warner for the most part stayed on the same page during the Russia investigation, while their House counterparts, Democratic intel chairman Schiff and Devin Nunes, the ranking Republican, waged open political warfare. The same dynamic played out when DNI Joseph McGuire came before the House committee Thursday.

The last thing Burr wants is another politically divisive probe, sources close to the committee say. But while few Senate Republicans have embraced the widely held Democratic view that Trump acted improperly, some have said the Ukraine case exposes a loophole in the intelligence community whistleblower process that may require a legislative fix — namely, that an intelligence officer could file a serious complaint, only to have lawyers block it from being sent to Congress on technical grounds.

Senate Democrats for the most part believe the import of the Ukraine case goes far beyond the narrow issue of whistleblower protection, but if Warner were to say that publicly, there is every chance Burr would pull the plug on the bipartisan inquiry, the sources say.

Burr warned reporters, "Don't expect us to move at lightspeed. That'll probably happen in the House."

If the Senate Intelligence Committee runs a bipartisan investigation that concludes some level of wrongdoing by Trump, that could have an impact on any Senate vote on impeachment articles.