WHITE HOUSE - A defiant President Donald Trump flatly denied Thursday that he had pressured the FBI to close its investigation of a former close aide, and he questioned the need for a special counsel to probe possible collusion between his 2016 campaign and Russians trying to influence the presidential election.
"No, no. Next question," he replied when a reporter asked whether he had asked then-FBI Director James Comey to back down on the bureau's probe into fired national security adviser Michael Flynn.
At his first news conference since April 12, standing alongside visiting Colombian President Juan Manuel Santos, Trump denied there had been any collusion between himself, his campaign and Russian agents of influence. "Even my enemies say there was no collusion," he said.
But he added a qualifier that seemed to leave open the question of others' involvement. "I can only speak for myself and the Russians. Zero."
Trump lamented that the controversies swirling around the White House were damaging national unity. "I think it divides the country," he said. "I think we have a very divided country because of that and many other things."
Those comments followed a pair of early-morning Twitter posts questioning the need for the appointment of former FBI Director Robert Mueller as a special counsel to look into the collusion allegations.
This is the single greatest witch hunt of a politician in American history!— Donald J. Trump (@realDonaldTrump) May 18, 2017
With all of the illegal acts that took place in the Clinton campaign & Obama Administration, there was never a special counsel appointed!— Donald J. Trump (@realDonaldTrump) May 18, 2017
"With all of the illegal acts that took place in the Clinton campaign & Obama Administration, there was never a special counsel appointed!" the president tweeted.
WATCH: Trump comments on appointment of special counsel
Later, at a luncheon with prominent TV network news anchors, Trump said the appointment of a special prosecutor "hurts our country."
Trump's comments came as Deputy Attorney General Rod Rosenstein, who appointed Mueller as special counsel, went to Capitol Hill to brief the entire Senate behind closed doors.
The president was the only administration figure speaking publicly Thursday, furthering speculation that he has effectively muzzled White House surrogates who often speak for him. News reports have characterized the president as dissatisfied with his communications team's inability to control the tenor of the coverage of recent negative stories.
The usually forthcoming White House spokesman Sean Spicer, meeting reporters Wednesday, dodged questions about Comey and the Russian connection, referring reporters to a terse White House statement issued the day before. News reports over the past few days have said Spicer and other communications team members may soon be replaced in a White House shake-up.
The news website Politico quoted a White House adviser as saying there was a struggle to get any surrogates on TV because no one knew what to say or how to defend the story.
When news broke this week of the Comey memo on Trump's alleged interference in the Flynn investigation, Fox News commentator Charles Krauthammer said he found it "really stunning that nobody, not even from the White House, has come out under their own name in defense of the president here."
WATCH: Trump to help stop drug violence in US, Colombia
Presidential historian Dan Mahaffee of the Center for the Study of Congress and the Presidency sees parallels between what is happening in the Trump White House and similar moments in other beleaguered administrations.
"We see the common theme that in any presidential scandal, the attempt to either cover it up, hide it, obfuscate, is what drives the narrative," Mahaffee said.
"So whether it is the famous Saturday Night Massacre with [Richard] Nixon that led to attention on Watergate, [Ronald] Reagan's Iran-Contra arms-for-hostages scandal, or then with [Bill] Clinton, it was the attempt to obfuscate," he said. "In this administration, we see that the agenda seems to be completely derailed by the desire to fight this and push back on the story."
Instability roils markets
Financial markets recovered somewhat Thursday following a sharp downturn a day earlier after news broke of the special counsel's appointment.
Emily Stewart, a political reporter for the financial website TheStreet.com, said investors are frightened by the prospect of prolonged political instability.
"It does make people nervous that a tax cut may not come to boost earnings this year," Stewart said. "What if it doesn't come in 2018, especially since midterm elections are approaching? And if Congress is going to spend so much time and energy looking into the Trump administration, how much time do they have for taxes and health care"?
Trump is clearly hoping to change the negative news flow when he heads off this weekend for a nine-day foreign trip where he will meet with dozens of Muslim heads of state, the leaders of Israel and the Palestinians, Pope Francis, and leaders of NATO countries and the Group of Seven industrialized nations.