(CNN) President-elect Donald Trump said for the first time Wednesday he believes Russia was responsible for hacking ahead of the election but contemptuously rejected allegations that Moscow mounted a campaign to compromise him.

In his first news conference since winning the election, a combative Trump made clear he will not mute his style when he is inaugurated in nine days. He lashed out at media and political foes alike in a bravura performance.

The Trump Tower press conference confirmed the President-elect's deep desire to quickly assert power once he's sworn in. He insisted on moving speedily -- too speedily for some Republicans in Congress -- to replace Obamacare. He also pledged swift action on building a wall along the border with Mexico and nominating a new Supreme Court justice.

But it's also clear Trump will take office amid persistent questions about his relationship with Russia. While Trump was at the podium, his nominee to become secretary of state, Rex Tillerson, faced tough questions on Capitol Hill about whether the incoming administration will view Russia with sufficient skepticism. At the news conference, Trump finally conceded he believes Russian President Vladimir Putin's intelligence agencies were behind hacks on Democratic computers ahead of the election but argued that wouldn't happen again.

"I think it was Russia," Trump said. Putin "should not be doing it. He won't be doing it. Russia will have much greater respect for our country when I am leading it than when other people have led it."

Trump, who has vowed to improve relations with Russia despite some Republican opposition, said he did not know if he would get along with Putin and noted it's possible he won't. But he could not resist a swipe at his defeated Democratic election rival, Hillary Clinton.

"Do you honestly believe Hillary would be tougher on Putin than me?" he asked.

He added that Russia is not the only nation that hacks US targets and accused Democrats of not having sufficient cybersecurity programs.

'Witch hunt'

The news conference opened with the incoming White House press secretary, Sean Spicer, slamming a "political witch hunt" following reports that Russian operatives claim to have compromising personal and financial information about Trump.

Vice President-elect Mike Pence also criticized the media before introducing Trump, who kept up his criticism of US intelligence.

"I must say that I want to thank a lot of the news organizations here today because they looked at that nonsense that was released by maybe the intelligence agencies," Trump said.

He said any such move by the agencies would be a "tremendous blot on their record."

"A thing like that should never have been written, it should never have been had and it certainly should have never been released," Trump said.

The news conference follows exclusive reporting by CNN on Tuesday that classified documents presented last week to President Barack Obama and Trump included the allegations about Russia. The allegations were presented in a two-page synopsis that was appended to a report on Russian interference in the 2016 election and drew in part from memos compiled by a former British intelligence operative, whose past work US intelligence officials consider credible.

The FBI is investigating the credibility and accuracy of these allegations, which are based primarily on information from Russian sources, but has not confirmed many essential details in the memos about Trump.

Conflicts of interest

The news conference, delayed from December, was scheduled for Trump to outline how he will address questions about possible conflicts-of-interest related to his vast business empire. Trump appeared beside a large pile of files he claimed were pertinent to the companies that are going to be placed in a trust to be run by his sons.

He reiterated that he doesn't plan to release his tax returns, saying they are under audit and don't include relevant information

Trump will leave business, but won't sell

After taking a handful of questions, Trump turned the event over to Sheri Dillon, an attorney who was on hand to discuss Trump's business interests. She said Trump planned to put in place a structure that will "completely isolate him from the management of the company."

"He further instructed that we build in protections that will assure the American people that the decisions that he makes and the actions he takes as President are for their benefit and not to support his financial interests," she said.

Trump will place all his financial and business assets in a trust, Dillon said. The Trump Organization, meanwhile, will not enter into any new deals abroad and all domestic deals will be subject to a heavy vetting process. The firm will also appoint a new ethics officer, she said. The President-elect has also terminated a number of deals set to close shortly, a step that had cost him millions of dollars, she said.

Dillon argued that the decision had been made not to put all Trump's assets in a blind trust or to divest of all his assets because it would be impractical. She also said that Trump should not be forced to destroy the business that he had built up.

"President Trump can't unknow he owns Trump Tower," Dillon said, explaining why a blind trust would not be a workable solution to addressing conflicts of interest issues while he is President.

Dillon said Trump would take other actions to avoid the appearance of a conflict over the Emoluments Clause of the Constitution, which prohibits the president from accepting gifts from foreign governments unless authorized by Congress. She said it was unfair to apply the clause to Trump's "arm's length" transactions that he had nothing to do with or was not aware of.

"Just like with conflicts of interests, he wants to do more than what the Constitution requires," she said. "President-elect Trump has decided and we are announcing today that he is going to voluntarily donate all profits from foreign government payments made to his hotels to the United States Treasury."

Obamacare, border wall, Supreme Court

When he returned to the podium, Trump turned to policy, vowing to press ahead with a near simultaneous repeal and replacement of Obamacare at the same time, rejecting the approach of some Republicans on Capitol Hill who worry that rushing could create problems.

"It will be repeal and replace. It will be essentially simultaneously," he said, saying the two goals would be accomplished in the same week, day or even hour.

Trump reiterated that he will build a wall on the southern border and Mexico will pay for it, but defended his decision to ask Congress to fund it initially.

"We are going to build a wall," he said, adding that he didn't want to wait a year and a half to finish negotiating how Mexico would pay for it. "Mexico, in some form ... will reimburse us."

He added that the financing was more likely to take the form of a tax than a payment.

The President-elect also said he had been looking at the list of 20 potential Supreme Court nominees he had proposed to replace late Justice Antonin Scalia.

He said he would announce his decision "within two weeks of the 20th, probably the second week."