Perplexed viewers are questioning Robert Mueller's 'confused' demeanor as he testifies in front of Congress.

The special counsel faced members of the House Judiciary and Intelligence Committees on Wednesday morning at a highly-anticipated hearing on the Russia investigation.

Viewers reacting on social media have noticed that Mueller appeared to stumble at multiple points.

'Robert Mueller comes across as a doddering old fool with a questionable moral compass based on situational ethics who should never have been appointed in the first place based on reduced mental capacity,' one person tweeted.

'Mueller is acting like he doesn't know what's going on,' another wrote. 'He's acting like a confused old man.'

Some are saying the wobbly performance is a delaying tactic on the part of the special counsel to frustrate Republican committee members determined to discredit findings that are damaging to President Donald Trump.

When it came to questions at the core of the report, Mueller has delivered firm answers without hesitation.

Asked whether Trump had been exonerated or if he could be charged with obstruction of justice when he leaves office, Mueller replied: 'No' and 'Yes' respectively.

'Lots of twitter folks are dogging Mueller out for looking old and feeble,' MSNBC's Joy Reid tweeted. 'But optically, that just makes the Republicans yelling at him look more absurd. Mueller is quite definitive in his one word answers, which only Dems are eliciting from him so far.'

Perplexed viewers are questioning Robert Mueller's 'confused' demeanor as he testifies in front of members of the House Judiciary and Intelligence Committees on Wednesday morning

Viewers reacting on social media noticed that Mueller appeared to stumble at multiple points

MSNBC's Joy Reid defended Mueller's performance, saying his answers have been effective

Several Twitter users expressed the opinion that the 74-year-old veteran prosecutor's shaky demeanor calls his entire report into question.

'Listening too Mueller the cracking in his voice shows clearly that he is a conflicted Skunk and lying ! And I think he is senile !'

'As I said when Mueller gave speech in May, he is feeble,' radio personality Mark Levin tweeted. 'I say that not as a personal attack but as a rational observation. It's on display today during this hearing.

'This underscores that the person who influenced this investigation most was Andrew Weissman, his top lieutenant.'

Replying to Levin's tweet, one man wrote: 'Agreed, Mueller looks geriatric and lost.... find that man a time machine.'

'It's quite entertaining. Mueller can't make a coherent statement. Looks like the circus made a stop in DC,' a woman tweeted.

'I'd say Democrats right now regretting they ever subpoenaed Mueller. He looks confused,' a man wrote.

Some viewers have said Mueller's shaky demeanor calls his report into question

Others think Mueller sounds uncertain because he is being overly-cautious about coming off as impartial.

'I'm concerned that Mueller is so concerned with not appearing political that he is really under-performing at times by failing to clarify things that need clarification,' one woman wrote.

'To let crazy GOP statements stand without clarification could be interpreted as agreement.'

Some noted that Mueller is being hindered by the mammoth task of manually searching through 397 pages to effectively answer questions about the report his team took two years to compile.

He repeatedly had to ask committee members for page numbers when asked to comment on specific sections.

One woman tweeted that Mueller would have a much easier time referring to the report if he had searchable copy on a computer.

'Give Robert Mueller a computer, he desperately needs CTRL + F,' Vice Media VP Katie Drummond wrote.

Ironically, the copy of the report released by the Justice Department was a scanned printout and thus couldn't be searched. Several searchable versions have cropped up in the months since then.

Unfortunately for Mueller, witnesses are not allowed to use computers during hearings.

Mueller frequently had to pause and manually search through the 397-page report to effectively answer questions from lawmakers

Throughout the hearing, Democrats, who hold the majority on both committees present, worked to elicit short, definitive answers from Mueller.

House Judiciary Chairman Jerold Nadler asked him: 'Director Mueller, the president has repeatedly claimed that your report found there was no obstruction and that it completely and totally exonerated him. But that is not what your report said, is it?

'That is correct. That is not what the report said,' Mueller responding.

'Does that say there was no obstruction?' Nadler followed up later.

'No,' the former special counsel said.

'In fact, your report expressly states that it does not exonerate the president,' Nadler told him.

'Yes it does,' Mueller replied.

Most of Mueller's fumbles came in response to Republicans trying to get him to stray from his typical dry, technical explanations.

'Where are you reading from?' he asked one member, Rep James Sensenbrenner. 'I am reading from my question,' the Wisconsin Republican lawmaker told him.

Under questioning by Republican Rep Steve Chabot, Mueller didn't show immediate familiarity with political intelligence firm Fusion GPS, a key player in the trail of the Steele Dossier, and a fixture of attention of President Trump and GOP critics of the Mueller probe.

'When you talk about the firm that produced the Steele reporting, the name of the firm was Fusion GPS, is that correct?'

'I'm not familiar with that,' said Mueller.

'That's not a trick question. It's Fusion GPS.'

Most of Mueller's fumbles came in response to Republicans trying to get him to stray from his typical dry, technical explanations

Ohio Republican Rep Jim Jordan sought to draw Mueller out on the surveillance warrants for former Trump campaign adviser Carter Page, whose trips to Russia drew attention of investigators.

'Director Mueller, the third FISA renewal happens a month after you're named special counsel. What role did your office play in the third FISA renewal of Carter Page?' Jordan asked.

'I'm not going to talk to that,' said Mueller.

In his prepared statement, Mueller began by defending his probe following an onslaught of attacks, and spelling out questions he will and will not answer.

He said he told his team at the start of the Russia probe to 'work quietly, thoroughly and with integrity so that the public would have full confidence in the outcome.

'We needed to do our work as thoroughly as possible and as expeditiously as possible. It was in the public interest for our investigation to be complete and not to last a day longer than necessary,' Mueller said.

He said his team of lawyers and agents worked 'fairly and with absolute integrity' – minutes after President Trump once again attacked it as a 'witch hunt'.

'Our team would not leak or take other actions that would compromise the integrity of our work,' said Mueller. 'All decisions were made based on the facts and the law.'

Ohio Republican Rep Jim Jordan sought to draw Mueller out on the surveillance warrants for former Trump campaign adviser Carter Page, whose Russia trips drew investigators' attention

Rep Doug Collins tried to get Mueller to contradict his report by asking him whether 'collusion' and 'conspiracy' are the same thing after Mueller testified that they weren't.

Collins cited a portion of the report that states: 'Collusion is not a specific offense or theory of liability found in the U.S. Code; nor is it a term of art in federal criminal law. To the contrary, even as defined in legal dictionaries, collusion is largely synonymous with conspiracy as that crime is set forth in the general federal conspiracy statute.'

Mueller critics declared that the special counsel had been bested by Collins, while experts explained that Collins' citation was taken out of context.

The part of the report in question was about collusion in the sense of corporate collusion - when companies conspire in an illegal fashion to help each other at consumers' expense.

Corporate collusion is unrelated to 'collusion with Russia', the colloquial term adopted in the debate about potential cooperation between the Trump campaign and the Russian government.

Both sides sought to get Mueller on record on the question of whether he had any potential conflict that would prevent him from overseeing the probe.

Georgia Democrat Rep Hank Johnson asked Mueller if he had any conflicts of interest that prevented him from being special counsel. Mueller said he did not. Trump has repeatedly said Mueller was 'highly conflicted,' saying he had interviewed to be his FBI director and that the two men had a nasty business dispute.

Some people on social media lambasted Republican committee members for trying to damage Mueller's credibility.

'No matter your political party, it’s absolutely disgusting to see those attacking Mueller's integrity,' one man tweeted.

'The way the @JudiciaryGOP members talked and yelled at Robert Mueller is beyond awful. They've all lost their souls,' another wrote.

'Republicans can't argue the facts, so they attack the investigation and the investigators,' another said.

'Remember this slander of Mueller the next time you hear republicans going on about their love & respect for veterans. They will throw anyone under the bus who doesn’t toe the party line.'

Some people on social media lambasted Republican committee members for trying to damage Mueller's credibility