"Congressman, I am not here to be a puppet to repeat terms and words that you say that I should say", Whitaker told Swalwell Friday.
He said he had not taken any action to interfere "in any way" with the probe.
Whitaker was a skeptic of Mueller before he came to work for the department, but he said his criticisms were based on the views of an outsider and that he's since gotten a better understanding of the case as acting attorney general. He also said all Whitaker received the questions weeks ago so they would know ahead of time which were subject to executive privilege.
The dispute emerged amid reports that Democrat and committee chairman Jerrold Nadler was planning to subpoena Mr Whitaker to testify about his interactions with President Donald Trump. Trading Whitaker in for him will be one of the Trump presidency's rare blessings.
The testimony comes as Whitaker is likely winding down his tenure leading the Justice Department with the nearly certain confirmation of Attorney General nominee William Barr in the coming weeks.
Monetary Policy: RBI cuts key policy rate to 6.25%
GDP growth for 2019-20 is projected at 7.4% - in the range of 7.2-7.4% in H1, and 7.5% in Q3 - with risks evenly balanced. With inflation largely under control, the big concern for the government is growth, particularly in an election year.
Representative Doug Collins of Georgia, the panel's top Republican, said Democrats were staging a "dog-and-pony show" simply "to damage the president".
The hearing is scheduled to begin at 9:30 a.m. ET.
She also brought up Trump's attacks on the DOJ and the Federal Bureau of Investigation.
"You decided that your private interest in overseeing this particular investigation, and perhaps others from which you should have been recused, was more important than the integrity of the department", said Nadler, of NY. Democratic Texas Rep. Sheila Jackson Lee held up a copy of the Constitution and became outraged when Whitaker refused to answer her questions with "yes" or "no".
He said he had "consulted with a lot of people" about the options, but it was ultimately his choice.
Whitaker: "Mr. Chairman, your five-minutes are up".
Get Brussels to talk and we will give you more time
Speaking during a trip to Japan, Ms Merkel said: "To solve this riddle, you have to be creative and you have to listen to one another".
'In your capacity as acting attorney general, have you ever been asked to approve any action or request to be taken by the special counsel?' he asked. "You don't run this committee!"
So far, the hearing has not shed much light on the status of the Mueller investigation - and it may not.
"Mr. Attorney General, we are not joking here and your humor is not acceptable", she said. The president has also said there was no collusion between his campaign and Russian Federation.
"It's getting a little tiresome hearing you stall", the New York Democrat told Whitaker.
Democrats said they would inquire about Whitaker's past business dealings, too.
In agreeing to appear before the Judiciary panel, Whitaker sidestepped a confrontation with Democrats over threats to subpoena him. He also signaled that he would give limited answers about the investigation itself.
Sudden outbreak of measles prompts emergency declaration, renews vaccination debate
A vast majority of those who came down with measles - 41 - were not vaccinated against the disease, Clark County officials said. NY is experiencing a measles outbreak within observant Jewish communities stemming from travel to Israel.