President Trump's critics are now complaining that he asked the Australian prime minister to cooperate with the Justice Department's investigation into the origins of the Mueller probe and that Attorney General William Barr has traveled overseas to ask foreign intelligence officials to cooperate with that investigation.

The New York Times called it another example of "the president using high-level diplomacy to advance his personal political interests."

No, it's not. The president's critics are conflating two different things: the investigation by Trump's private lawyer, Rudolph Giuliani, into Hunter Biden's business dealings, and the official inquiry by U.S. Attorney John Durham into the counterintelligence investigation directed at the Trump campaign during the 2016 election.

The former is opposition research activity; the latter is a criminal justice matter.

There is absolutely nothing wrong with asking foreign heads of state or intelligence officials to cooperate with an official Justice Department investigation. As George Washington University law professor Jonathan Turley explains: "It is not uncommon for an attorney general, or even a president, to ask foreign leaders to assist with ongoing investigations. Such calls can shortcut bureaucratic red tape, particularly if the evidence is held, as in this case, by national security or justice officials."

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Americans support the Durham probe. For two years, they were told by Trump's opponents that the president was "working on behalf of the Russians" and had committed "treasonous" acts that were of "a size and scope probably beyond Watergate."

Those were serious accusations, and Americans took them seriously. They waited for Special Counsel Robert Mueller to tell them whether the president had indeed betrayed the country.

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Then Mueller issued his report, and they found out that none of it was true. They understandably wanted answers.

How did it come to pass that our government was paralyzed for two years and spent tens of millions of their tax dollars, chasing a Trump-Russia collusion conspiracy theory?

A Harvard CAPS-Harris Poll following the Mueller report's public release found that 53 percent of Americans said that "bias against President Trump in the FBI played a role in launching investigations against him," and 62 percent supported appointing a special counsel to investigate the investigation of Trump.

Instead of a special counsel, Barr appointed Durham, a career prosecutor, to lead the investigation that Americans demanded. Durham is a man of unimpeachable character who was appointed by Obama administration Attorney General Eric Holder to investigate the CIA's terrorist interrogation program.

At the conclusion of that probe, which ended without any criminal charges, Holder praised Durham for working "tirelessly to conduct an extraordinarily thorough and complete" investigation.

Now Barr has asked Durham to bring the same tireless professionalism to his investigation into the origins of the Mueller probe. But suddenly, all those who were so eager to find out what happened in 2016 when they thought Mueller would reveal that Trump conspired with the Russians have lost interest.

The same people who were outraged at Trump's efforts to discredit the Mueller probe are now doing the exact same thing to the Durham probe. Back then, Democrats insisted Trump stop criticizing the investigation and "let Mueller follow the facts wherever they lead." Now they need to heed their own advice: Stop criticizing the investigation.

Let Durham follow the facts wherever they lead. If there was no wrongdoing, then there is nothing to worry about.

To be sure, Trump bears some responsibility for helping Democrats lump together Durham's official investigation with Giuliani's partisan activities by mentioning them both on the call with Ukraine's president.

There should be a firewall between the two inquiries. Instead, Trump and Giuliani have blurred those lines.

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But keep in mind, it was Democrats who told us there is nothing wrong or illegal with a presidential candidate hiring a private lawyer to conduct opposition research in a foreign country on their political opponents. After it emerged that the Clinton campaign and the DNC had paid Christopher Steele to dig up dirt in Russia on Trump, the Democrats' defense was: That's just opposition research. Everyone does it.

The biggest problem with the Steele dossier was not that Democrats paid for opposition research, but that the FBI might have used it as the basis for spying on the Trump campaign – which is part of what Durham is investigating.

Durham is no partisan actor. Despite political pressure, he cleared the CIA of wrongdoing during the Obama administration. Like Mueller, he will follow the facts wherever they lead. Maybe that is why so many Democrats are up in arms.

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