Democrats immediately seized on President Donald Trump's tweet Wednesday in which he urged Attorney General Jeff Sessions to end special counsel Robert Mueller's Russia probe.

"This is an attempt to obstruct justice hiding in plain sight," said Rep. Adam Schiff, D-Calif., the ranking member on the House Intelligence Committee.

But legal experts said it's not that simple, particularly as Mueller and his team are reportedly looking at Trump's tweets as part of a wider investigation into potential obstruction.

Read more: Trump is tweeting the term "witch hunt" a lot more frequently these days

"Donald Trump's morning stress-tweeting-storm definitely adds to a strong case that the president has obstructed justice," said Jennifer Taub, an expert in white-collar crime who teaches at Vermont Law School. Taub noted, however, that Mueller "will assemble an entire picture, not just rely on a single piece of the puzzle."

Sol Wisenberg, a leading white-collar attorney who was deputy independent counsel during the Clinton-era Whitewater investigation, said the "tweets alone do not come close to constituting obstruction of justice." But Wisenberg said that the tweets might be used by prosecutors to argue that Trump is guilty of a separate crime.

"His tweets could be used as proof of his efforts to shut the investigation down. Why would you want to shut the investigation down if you did nothing wrong in the first place?" Wisenberg said.

Trump has repeatedly denied colluding with Russians to attack the 2016 election. He has also denied that he has obstructed justice.

Mueller is scrutinizing tweets and negative statements from the president about Sessions and fired FBI Director James Comey to see whether the actions add up to attempts to obstruct the investigation, The New York Times reported last month.

The president's comments Wednesday seem to show that Trump has not been deterred by Mueller's interest in his tweets.

"Attorney General Jeff Sessions should stop this Rigged Witch Hunt right now," the president wrote on Twitter. "Bob Mueller is totally conflicted, and his 17 Angry Democrats that are doing his dirty work are a disgrace to USA!"

In recent weeks, Trump and his legal team have escalated their attacks on the inquiry. Trump's lawyer Rudy Giuliani sparked headlines Monday morning by saying "collusion is not a crime." The president echoed those sentiments in another tweet Wednesday morning.

"The president is not obstructing, he is fighting back," White House press secretary Sarah Huckabee Sanders said during a briefing with reporters later Wednesday. Sanders also said the tweet was an opinion and not an order.

Robert Ray, a partner at Thompson & Knight and another Whitewater independent counsel, agreed that the president's tweet about Sessions and the Mueller probe did not constitute a crime.

"And, more importantly, even if the tweets could be seen as an implicit direction to shut down an investigation, the president is within his constitutional prerogative in doing so," he said. "If Congress sees fit to impeach him for it, so be it. But, such an effort by the President most assuredly, in my view, is not a crime."