Julian Zelizer is a history and public affairs professor at Princeton University, editor of " The Presidency of Barack Obama: A First Historical Assessment " and co-host of the "Politics & Polls" podcast. Follow him on Twitter: @julianzelizer . The opinions expressed in this commentary are his own.

(CNN) On Sunday, President Donald Trump unleashed a tweetstorm, which culminated with his "demand" for an investigation into whether the FBI tried to infiltrate his campaign. In response, Department of Justice Spokesperson Sarah Isgur Flores issued a statement, saying the DOJ would ask its Inspector General to expand its review to address the President's concerns. While Trump's latest move is contentious, it's hardly surprising.

The demand comes after several months, during which Trump has been actively working to delegitimize the Russia investigation being conducted by special counsel Robert Mueller. Rudy Giuliani, who has joined the Trump legal team, backed the President's call for an investigation, said Trump would not agree to an interview with Mueller before learning more about the role of an FBI confidential source who was in contact with people connected to the Trump campaign, and said Mueller had told him the investigation could be wrapped up by September.

Trump's attacks have been effective.

So far, the political tide has turned in his direction. The House Republicans have essentially shut down any pretense of a serious investigation. More Republican voters are saying that they are skeptical about Mueller's inquiry. And much of the news coverage has shifted to claims that Trump has been making about the investigation rather than findings of the investigation itself. To be fair, Mueller has kept a tight lid on the investigation, leaving somewhat of a vacuum in which Trump's criticisms have had free rein.

A president striking back at his investigators is not a new phenomenon. President Bill Clinton was able to paint the Republican Congress as overzealous partisans in 1998 working with a conservative prosecutor, Ken Starr, to bring about his impeachment. President Richard Nixon secretly asked his staff to have the CIA stifle the FBI.

Trump has gone even farther by pushing a story about a dangerous "deep state" trying to subvert an election and suggesting that the investigation is just an effort to destroy his presidency -- using a Republican, Robert Mueller, as the point man.

It will be difficult for the investigators to reverse the damage that has been done. The FBI and DOJ are reluctant to publicly respond in any way that makes them appear political. Deputy Attorney General Rod Rosenstein is trying to avert a showdown between Justice and the President. Sunday night he announced that the inspector general will investigate. But by tweeting the accusation, the President has already cast the doubt in the public mind.

And when Democrats raise their concerns about what is happening, most Republicans dismiss their warnings as partisanship. Democrats also lack the institutional muscle on Capitol Hill to move forward with their concerns.

At this point, the only foreseeable game changer could be Mueller's final report. He might paint a detailed picture that is so dire and so damning that it fundamentally alters the political dynamics in Washington. But it also might be too late -- regardless of what it says.

By the time that Mueller is finished, Trump might have succeeded in turning the tables on the investigators. He might also be able to make progress on a bold diplomatic agreement with North Korea that would make him look more like Ronald Reagan after he signed the INF Agreement (which eliminated certain types of missiles) with the Soviet Union than the Ronald Reagan under the glare of the Iran Contra scandal.

We live in an age when narratives really matter in politics. The way that the public understands an issue and the stories that the news media focuses on can be crucial to the political outcome of a struggle. As we have learned, the facts don't always win.

This weekend, Trump took his campaign to a new level, and the impact of his statement should not be underestimated.

If the charges that Trump made were based on hard facts and rock-solid evidence, then the right thing would be for the President to rely on the established channels of oversight -- such as the Office of the Inspector General of the Justice Department -- and handle this allegation outside the purview of the public.

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But Trump is interested in politics. What we are seeing is an aggressive use of executive power where the point is not to find out about wrongdoing but to undercut the strength of those whom he sees as his opponents.

Whatever happens to Trump, his attacks on the key institutions of American law enforcement and intelligence agencies could well have a damaging long-term impact, as more of his followers accept the idea that organizations like the FBI can't be trusted.