President Trump's personal attorney Rudy Giuliani says it's his right to travel to Ukraine to "defend" his client -- to try to push for investigations that he thinks could be "very helpful" to the president. The New York Times first reported Giuliani's travel plans -- he told the Times that he plans to ask Ukraine's new president, Volodymyr Zelensky, to look into the origins of special counsel Robert Mueller's Russia investigation, as well as former Vice President Joe Biden's son's past connections to the country.

He said there's "nothing illegal" about his effort to pursue probes in Ukraine, since he is not trying to carry out foreign policy initiatives on behalf of the administration.

"[T]his isn't foreign policy — I'm asking them to do an investigation that they're doing already and that other people are telling them to stop. And I'm going to give them reasons why they shouldn't stop it because that information will be very, very helpful to my client, and may turn out to be helpful to my government," he told the Times.

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Late Friday morning, Giuliani tweeted, "Explain to me why Biden shouldn't be investigated if his son got millions from a Russian loving crooked Ukrainian oligarch while He was VP and point man for Ukraine. Ukrainians are investigating and your fellow Dems are interfering. Election is 17 months away. Let's answer it now."

In an interview on Fox News' "The Ingraham Angle" Thursday night, Giuliani said that as Mr. Trump's lawyer, he has an obligation to develop "explanations of what [his] client was charged with."

"The fact is, this was a massive collusion between the Democratic National Committee, officials of the Obama administration, (Hillary) Clinton people, and the Ukrainian officials, corrupt officials -- who, by the way, were pro-Russian corrupt officials -- to create false information about Trump, about (Paul) Manafort," Giuliani explained.

"This is -- this is real -- not collusion, conspiracy to present false information, and to leak it to the press, and to give it to the FBI," he claimed.

Is there a double standard: Democrat alleged wrongdoing is ignored and Republican exaggerated and sometimes falsely. The media blackout of the investigations in Ukraine of alleged Democrat corruption is further proof of a double standard. If it involved Republicans, headlines. — Rudy Giuliani (@RudyGiuliani) April 28, 2019

It's an accusation Giuliani has brought up several times, charging that the news media has ignored allegations of Democratic corruption involving the Ukrainian government, and that DNC officials tried to "set up" members of the Trump campaign in 2016 with "false information" about Mr. Trump. Giuliani maintains that there's a double standard when Democrats' alleged wrongdoing is ignored," while accusations against Republicans are "exaggerated and sometimes falsely."

Attorney General William Barr has assembled his own team to investigate how the Russia investigation began, a U.S. official told CBS News. Barr said in a Congressional hearing that he is "reviewing the conduct of the investigation and trying to get my arms around all the aspects of the counterintelligence investigation that was conducted during the summer of 2016."

At the same time, the Justice Department's inspector general is also investigating the Justice Department's early handling of the Russia investigation, which predates Barr's tenure at the department. He became attorney general after concerns had already been raised in the Justice Department that it might be too easy to open an investigation.

Giuliani previously paid a visit to Ukraine as part of his work for Giuliani Security & Safety, which offers foreign governments and multinational corporations a "full platform of security, investigative and crisis management services," according to the firm's web site.

He also traveled to Kharkiv, Ukraine, in November last year as part of the firm's work to help improve security in the city.

Since the release of the Mueller report, after a nearly two-year long investigation into any involvement by Trump associates in Russian meddling in the 2016 election, congressional Democrats have pushed for the full unredacted release of the report. They have issued sweeping subpoenas calling on White House officials to turn over any documents pertaining to the probe.

But the White House is trying to block most of these efforts, most recently announcing that the president would be claiming executive privilege over the entire Mueller report and the underlying documents. The president has also vowed to fight "all the subpoenas" from Capitol Hill.