Julian Zelizer is a history and public affairs professor at Princeton University and the editor of "The Presidency of Barack Obama: A First Historical Assessment," a new book that Princeton University Press plans to publish this March. He's also the co-host of the "Politics & Polls" podcast. The opinions expressed in this commentary are his own.

(CNN) Democrats should not be fooled by the turbulence that came at the end of the week for this administration. With stock markets falling 666 points and outrage on the airwaves about the leaked memo, some Democrats might feel that this means President Donald Trump and the Republican Party are imploding. This is the moment Democrats have been waiting for.

But the President's opponents should not get too giddy. Even with the chaos and stock market turbulence, there are some strong signs that President Trump is in the process of mounting a political comeback.

Trump's approval rating has reached 42% -- up 10 points since December -- according to the latest Monmouth University Poll. Saturday morning, the President, citing the right-leaning Rasmussen poll, tweeted that his "approval rating jumped to 49%...So why does the media refuse to write this? Oh well, someday!"

Whether it's 42% or 49%, the fact remains that his approval rating is increasing. And Democrats are seeing some slippage in the generic ballot (it asks voters, without using specific names, whether they will vote for a Democrat or a Republican in the midterms) for November, which suggests that a "wave" election is not as inevitable as it looked just a few weeks ago.

Americans are feeling good

According to the latest Gallup Mood of the Nation poll, Americans are feeling pretty good right now -- compared with early 2017. Seventy-eight percent of those polled were pleased with the nation's military strength (up 12 points from last year); confidence in how secure the United States is from terrorist threats increased from 50% to 63%. Perhaps most important, consumer confidence is at a 17-year high.

In January, American employers added 200,000 jobs and wages spiked. Yes, the stock market fell, but it remains at historically high levels. And this month, workers' paychecks will grow a bit bigger as the new IRS tax withholding tables register the impact of the tax cut that passed in December.

To be sure, the massive wave of retirements from Republicans in Congress, the overall poll numbers and tumult that President Trump will inevitably continue to create, still point to a good midterm election for Democrats. The sharp drop in the stock market Friday is a reminder that the key economic indicators can swing very quickly and those changes are hard to control. But the situation is changing and Democrats should not take some of the gains seen by this administration lightly and underestimate Trump once again.

Given how wrong the prognosticators were about who would win the 2016 presidential election, these signs of resurgence should be taken seriously.

How did this comeback begin?

The political dynamics in Washington started to change around Christmas, when President Trump shed any pretense of being a true economic populist and handed corporate America the big, fat whopping tax break that it had been waiting for since the start of his presidency. The tax cut was icing on the cake after a year when the administration quietly moved forward with deregulations for the corporate and financial sectors that were issued through executive action.

The tax cut was a huge victory for the GOP. Although the measure was extremely unpopular at the time of its passage, the bet seems to be paying off. Polls now show that approval for the measure has been steadily rising.

As long as the economic trends continue, President Trump and the GOP will be in good position to claim that it's Morning in America Again, to borrow President Reagan's phrase in 1984. Regardless of who deserves the credit for the economic boom, and regardless of the very real problems still facing millions of middle- and working-class families, the numbers are strong enough to be used by Republicans on the campaign trail as a sign of success.

Trump's version of Nixon's Saturday Night Massacre

In the Trump edition, nobody actually had to be fired. With all of the experts wondering whether President Trump would get rid of Robert Mueller or a high-level FBI official, the President, with the support of congressional Republicans, undertook a different strategy that is accomplishing the same goal. They moved to discredit the entire investigation through rumors, partisan memos, scandalous innuendo and character assassination.

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The President's Twitter feed has been an ongoing public relations machine to convince the country that the investigators are up to no good. The hoopla over whether or not President Trump would allow the infamous Republican memo to be seen was always beside the point. Once the news provided 24-hour coverage of the fact that some allegedly shocking memo was lurking in the committee room, the President had accomplished his goal.

It didn't really matter what was in the memo or that it was a partisan missive, just that something potentially scandalous existed. He had provided more fuel to the conspiratorial attacks the GOP has undertaken against the Russia investigation.

Although the public still supports Mueller's investigation and is dubious about the President's claims, the narrative of a "Deep State" and special investigator who attempted to throw an election and undertake a coup have taken strong hold in the national conversation. The release of the memo Friday will add fuel to the fire with its implication that the investigation was based on flawed information. In a memo that does not provide supporting intelligence and provides an incomplete portrait of how the investigation started, and why it continued, Republicans will claim to see evidence that the entire scandal was manufactured.

Trump boxed Democrats into difficult political position

The President has also made a pretty effective move on immigration. Before he became president, the young children of illegal immigrants who entered this country were protected by the "Dreamer" program that President Barack Obama implemented through executive action.

In an effort to strengthen support for his hard-line restrictionist immigration plan, which remains the centerpiece of Trump's New Deal, he created an artificial crisis by rescinding the entire program. He baited the Democrats into making the legislative restoration of DACA some kind of a deal, rather than this being the President's responsibility.

Democrats, who believe in government and governance, quickly buckled to a temporary budget that did not restore DACA. Now the President has raised the stakes by promoting a deal by which he would accept legislation restoring DACA, in a more expansive structure than before, in exchange for draconian measures on the rest of immigration -- from cutting off much the inflow of legal immigrants allowed by Lyndon Johnson's 1965 legislation to building his infamous wall.

Democrats are in a position of being the deciding force as to whether DACA survives, despite the fact they don't control any branch of government. He is pitting the Dreamers against the millions of other immigrants who won't be able to come here or won't be able to stay. He would take off the table the possibility of a path to citizenship for all the illegal immigrants who have been hoping for the kind of bolder agreement that Presidents Bush and Obama pushed unsuccessfully. Proponents of a liberalized immigration plan will have no more leverage.

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The Democrats have allowed the President to frame the negotiations on his terms . If they can't change the way this issue is being discussed, they will face a lose-lose situation. Either they will be held to blame for being responsible for ending DACA, which will deflate the party's base, or they will hand President Trump a massive legislative victory that could virtually cement his standing for 2020. The President would go into the midterm elections claiming that he achieved the "grand bargain," which eluded his predecessors, with legislation that liberalized certain parts of immigration while giving the hard-line right everything else that it wanted. He campaigned on building a wall and he will be able to say that he delivered. Minority leader Chuck Schumer has not been successful at keeping the focus on the GOP's responsibility to decide whether to keep DACA or deport hundreds of thousands of young people -- and might pay a steep price.

Trump still has the GOP's support

Finally, President Trump has been able to maintain partisan discipline. Despite all the complaints and big speeches from Republicans like Sens. Bob Corker and Jeff Flake, Republicans have generally remained supportive of the President—voting for his bills and avoiding any kind of proactive steps to tame his reckless behavior. The Washington Post reports that the Republican National committee is raising much more than the DNC.

Of course, President Trump remains incredibly vulnerable politically and his comeback is fragile. So, too, is the future of the Republican Party, which has now firmly thrown its reputation behind Trump and faces an extraordinarily challenging midterm election in November.

But President Trump has temporarily stopped the bleeding. Beneath the headlines about the Russia investigation is evidence that the administration is bouncing back and might be in stronger position going into the next set of elections than most of his opponents expected.