WASHINGTON (AP) — Senate Majority Leader Mitch McConnell told senators privately Tuesday he does not yet have the votes to block new witnesses in President Donald Trump’s impeachment trial.

McConnell convened a closed-door meeting of GOP senators shortly after Trump’s legal team made its closing arguments in the trial, the third and final day of defense proceedings punctuated by revelations from John Bolton, the former national security adviser. A Republican familiar with the meeting was not authorized to describe it by name and requested anonymity.

The GOP leader faced a handful of potential defections, but several days remained before any potential witness vote would be taken.

A decision to call more witnesses would need 51 votes to pass. With a 53-seat majority, Republicans can only afford to lose three Republicans to prevent more debate over witnesses.

McConnell has been trying to prevent a prolonged trial. Republicans were warned that subpoenaing testimony from Bolton or other witnesses could run quickly into legal challenges that could drag out for weeks.

But Sen. Mitt Romney, R-Utah, has said he wants to hear what Bolton has to say. Two other Republicans, Sen. Susan Collins of Maine and Sen. Lisa Murkowski of Alaska, also want to hear from more witness.

The White House has blocked its aides from appearing in the impeachment proceedings and would almost certainly claim some sort of executive privilege or national security objections over Bolton testifying.

One closely watched Republican, retiring Sen. Lamar Alexander of Tennessee, told reporters as he exited the private meeting he would wait for the next few days of the trial and make his decision.

Some senators have discussed trying to reach a deal with Democrats in which each side would call a witness — for example, Bolton and Hunter Biden, the son of former Vice President Joe Biden whose work in Ukraine has been referenced by Trump’s team in the impeachment proceedings. Such a deal, so far, has had few takers as most Republicans don’t want to hear from Bolton and few Democrats want to draw the Bidens into the impeachment proceedings.