'There are more text messages': Here's why Trump seems terrified by the impeachment hearings

MSNBC's Nicolle Wallace argued Tuesday that President Donald Trump's move to block Ambassador Gordon Sondland — a key figure in the Ukraine scandal — from testifying before Congress suggested he may fear what could be revealed in such hearings.

Sondland was involved in a series of conversations revealed in texts provided by former U.S. envoy Kurt Volker, which detail a damning back-and-forth among the diplomats and Ukraine. At one point, one State Department official, Bill Taylor, objects to what they're doing as a withholding "security assistance [from Ukraine] for help with a political campaign." Sondland replied, after more than four hours, with a legalistic reply denying any wrongdoing and saying they shouldn't text any further.

But Wallace noted: "NBC News has confirmed today that Sondland spoke with the president before sending that awfully on-message reply and adds that there are more text messages between the officials that haven't yet been released to the public. And if the substance of all those communications were something that White House lawyers felt so good about, seems to me Sondland would be up on Capitol Hill right now telling that story, and Donald Trump would be live-tweeting his own exoneration. But he's not."

Later, former Justice Department official Neal Katyal agreed.

"There's something huge going on here," he said. "Sondland is not just some person. He's a guy who works for you and me, the taxpayers. He's a public official. And they're blocking him from testifying. They must be scared that he's going to say something bad."

Watch the clips below: