Barack Obama, the charismatic former president, can cause a scene just by walking into a coffee shop, as the rapturous crowds in usually blase New York City demonstrated at one of his cameos. So as he gently re-entered the public and policy eye this week, it’s no surprise that he could throw both Democrats and Republicans off balance — though of course for very different reasons.

Senate Majority Leader Mitch McConnell gave President Donald Trump possibly his most important first-100-day achievement by spearheading the maneuver to transform Obama’s Supreme Court pick to replace Antonin Scalia into the conservative Neil Gorsuch, whose first significant vote allowed an Arkansas execution to proceed. McConnell’s obstruction and subsequent “nuclear option” may have played a part in breaking the democratic process, but isn’t that a small price to pay for a win —  at least I’m sure the president feels that way.

The Republican Congress and a Republican president, through executive orders, laws and public statements, have focused on undoing the Obama legacy, from immigration reform to climate change to criminal justice. Their major impediment, on, for example, the Affordable Care Act, has been the fractures within the party itself.

The former president’s appearance this week at his pre-presidency hometown of Chicago, moderating a panel of young future leaders on community engagement, was not outwardly political. But of course it was, as all the values he holds dear and the issues he chose to champion in and out of the White House run counter to the GOP playbook. Even the setting, in a city Trump has demonized, sent a message.

McConnell, the man who stymied Obama time and time again, could not quite put him away by making him that one-term president, as he promised at the midpoint of Obama’s first term. In his reappearance on the public stage, can Obama do anything to halt the assault on his legacy?

Payback?

The Kentucky senator must be wondering what the former president could possibly do to return the favor of McConnell’s disfavor.

Democrats, on the other hand, might be longing for some leadership after an ugly, dispiriting campaign that ended in big losses. But is the rested and ready Obama a reminder that it was under his leadership that the party lost big in state legislatures and governors’ races over eight years?

His large persona did not come with coattails in subsequent midterm elections, and the crowds’ cheers came with grumblings from Democratic Party pros that Obama was not that interested in grass-roots party building in 50 states.

Obama, as usual, is charting his own path. He always was an outsider, in some ways, who kept his own counsel. It may have appealed to an electorate in two presidential runs, but puzzled and frustrated politicians.

Though Democrats waved goodbye wistfully, they also need new faces for next steps, as polls show that the public may not like Republicans, but finds Democrats not in touch with concerns of the average person. Essential regrouping could be a lot more difficult when the glamorous prom king sort-of returns.

The fact that his guy, Tom Perez, beat progressive favorite Keith Ellison for Democratic National Committee chairman still rankles some as the party tries to stay united. That’s always been tough for Democrats, a trait on display in the Perez-Bernie Sanders road show.

The Obama family, each member with star power and a particular appeal — “Oh, Michelle,” her nostalgic fans wail — are now more welcome presences than the Clintons with a legacy tarnished with an unexpected and spectacular fall that will be the subject of books and misgivings till the end of time.

But the Democratic Party, a back bench depleted by all those state losses, also wants to go about the business of building star power. As Jon Ossoff, who was a whisper away from a first-round knockout in a House race in Georgia, and a-close-but-no-cigar finish for the Democrat in a Kansas special election prove, the road back will be rocky indeed.

On the plus side for Democrats, Obama’s influence could unite the party that showed togetherness after Trump’s win but is already breaking apart on issues such as abortion rights. He is supporting and taking an increasingly visible role in the fight by his former attorney general, Eric Holder, to break up the byzantine and ingenious redistricting and gerrymandering that have given Republicans in Congress and states an edge, even when vote totals favor Democrats.

Under Trump’s skin

Obama’s cool and popularity also seems to truly bother the new president. At Trump’s inauguration, he cozied up to and even courted the approval of the man he long said, using racially tinged, sinister and unproved accusations, was not a legitimate leader of the free world.

Then, he tweeted the charge — denounced by anyone with facts — that Obama wiretapped Trump Tower. Trump has continued to keep an eye on the man he reviles and admires, something that will be much easier as Obama tantalizingly ladles out public appearances here and there.

Republicans in Congress, with health care, tax reform and keeping the government open, have moved on in ways the new president has not.

Though out of office, Obama still seems to engender the passion that only abated when Hillary Clinton became the pinata of choice. Looking back can become a distraction when you’re trying to make progress and forge ahead.

Roll Call columnist Mary C. Curtis has worked at The New York Times, The Baltimore Sun and The Charlotte Observer. Follow her on Twitter @mcurtisnc3.