On a Friday in May, he delivers a commencement speech at Newark's Kean University, where, after he finishes, students shout "2020!" at the New Jersey Democrat. He then quickly boards an Acela train back to Washington for votes, where he offers to buy a fellow passenger coffee. The passenger responds by asking about his 2020 plans.

Everywhere Booker goes, the subject of a 2020 presidential run follows. And in the year-and-a-half since President Donald Trump was elected, Booker has spent about half his weekends on the road, visiting most states where a Democratic senator is facing a tough re-election fight, including multiple visits to Wisconsin, Ohio and Florida, as well as stops last year in Indiana and Montana, a recent swing through Minnesota and Missouri and a trip this weekend to Virginia.

It's his travel outside the Acela corridor, coupled with a series of legislative rollouts in the Senate, that is drawing the most attention from Democratic insiders and political observers who view his frenetic 2018 midterms schedule and policy moves as a wink-and-nod entry into the party's shadow 2020 presidential primary.

In an interview aboard the Acela, Booker says he'll make a decision about whether to run for president at the end of this year.

"I'm not going to play coy. I'm sure after the midterm elections, I'll give it a look," Booker said. "But to me, my momentum, my energy, my focus is 2018 and making sure I get re-elected in 2020."

His brain trust, which starts with chief of staff Matt Klapper and long-time political adviser Mo Butler and also includes adviser Brendan Gill, finance director Lauren Dikis and former campaign manager and friend Addisu Demissie, is keeping any preparations for a Booker 2020 run under wraps. And Booker's friends and allies say he has not made a decision about his own political future.

But Booker acknowledged the inevitability of the question of a presidential run.

"This is just this period where it's so premature to be thinking about 2020 and talking about 2020, even though clearly we are," he adds. "But I just think that, what I learned as mayor is if you take care of today really, really well, tomorrow is going to take care of itself, and the battle's going to be a lot easier."

In deciding about his political future, the 49-year-old Booker, a bachelor who most recently dated poet and artist Cleo Wade, acknowledged another concern that some close to him had raised: If he wants a family, the clock is ticking.

"Of all the titles that I sincerely seek in my life, more than anything else is ... to be a husband, and a father. And I've made tremendous sacrifices," Booker says.

Booker says his time as mayor of Newark, which he describes as a "24-hour mayor," hurt his personal life.

"I don't think about that in the context of a 2020 run; I think about it in the context of the career I've chosen. To be a senator, like right now, it's kind of hard to date when you're on the road, as I am right now, where your weekends are spent in three states," he says.

"Look, at a personal level, I really do think about that every day, because I really do think that one of the best titles you can have is a parent and a spouse," Booker adds. "So, anything I do, that's always a consideration, and I pray about it a lot."

Catch him if you can

On the trail, Booker's appeal is obvious: He is a dynamic and passionate speaker who can help white Democrats reach black voters, who make up a large share of the Democratic primary electorate.

Booker campaigned in Alabama last year, turning African-American voters out for Doug Jones in the state's Senate special election. He also visited two more deep-red states: Indiana and Montana.

Rural America is of particular interest to Booker. He recently read J.D. Vance's book "Hillbilly Elegy," about the lives of poor white people in parts of the country that overwhelmingly supported Trump in 2016. Now, he is planning a rural tour, which he said would be to learn about issues facing farmers with relatively little public attention.

"I just have this strong belief now as I meet rural, white Americans, as I meet rural black Americans, we have so much of the common pain but we're lacking the sense of common purpose," Booker said.

So far this year, Booker has visited Arizona, Ohio, Washington, Wisconsin, Florida, Minnesota and Missouri to support Democratic Senate candidates. He's also held events for Georgia gubernatorial candidate Stacey Abrams and Maryland gubernatorial hopeful Ben Jealous.

In order to free up more time for political travel, Booker asked his top New Jersey donors to skip their usual schedule of house parties and private gatherings this year. Instead, he invited them all to a massive fundraiser Thursday night in Newark, where he raised more than $500,000, a source familiar with the event said.

Steven Slugocki, the Democratic chairman in Maricopa County -- Arizona's largest and the home of Phoenix -- said Booker's camp agreed to a last-minute request to tack a stop at a local party event onto a January trip to raise money for Kyrsten Sinema's Senate campaign.

After the 300-person event at 8:30 p.m. on a Friday wrapped up, an aide tried to rush Booker back to his hotel.

"Cory, like, whispered into my ear, 'What are we doing now?'" Slugocki said. "He said, 'No, I want to take photos with everybody.'"

Booker lingered for more than an hour, Slugocki said, and took a selfie and another photo with every person who waited for one.

"Cory was honestly one of the nicest politicians I've worked with," Slugocki said. "He was friendly, he was fun, he took a genuine interest."

Booker as policy leader

In addition to the political travel, aides and advisers said Booker plans to use the rest of 2018 to introduce new legislation intended to offer parts of a Democratic agenda to counter Trump.

Already, Booker is at the forefront among 2020 Democratic prospects on legalizing marijuana. Several other possible contenders -- including New York Sen. Kirsten Gillibrand, Vermont Sen. Bernie Sanders and California Sen. Kamala Harris -- have signed onto Booker's bill.

Booker is also among the first Democrats to roll out a proposal for a federal jobs guarantee, calling for a pilot program in which 15 communities with high unemployment would receive federal money to offer every adult there a $15-an-hour job with health and family benefits.

Sen. Cory Booker (D-NJ) and Sen. Kirsten Gillibrand (D-NY) listen during a hearing before the Subcommittee on Emergency Management, Intergovernmental Relations, and the District of Columbia of Senate Homeland Security and Governmental Affairs Committee November 6, 2013 on Capitol Hill in Washington, DC.

In the coming months Booker plans to roll out more bills dealing with criminal justice as well as consumer protections, corporate consolidation and wages, an aide said.

The bills have no chance of becoming law under Trump and the Republican-controlled Congress. But Booker sees them as important markers of where Democrats would steer the country.

"My party has got to focus on not being anti-Trump. It's not about what you're against in life. It's what you're for," Booker says. "You've got to talk about the vision for the country and for where we're going. It's going to speak to people's hearts and heads, not their partisanship."

Booker's recent legislative moves have helped win over some progressives who have long seen the man who began his political career in Newark, in the shadow of New York City, as too close to Wall Street and pharmaceutical interests.

"The center of gravity in the Democratic Party is moving in an economic populist direction, and Cory Booker's efforts to improve on issues of corporate power show that he knows economic populism is popular with voters," said Adam Green, the co-founder of the Progressive Change Campaign Committee -- a group that brands itself as the "Elizabeth Warren wing" of the party.

Green specifically praised Booker's jobs guarantee proposal, saying that "voters will notice if he embraces more big ideas like that and shows an increased willingness to directly challenge corporate power."

Progressives were incensed last January when he voted against an amendment to a non-binding GOP budget resolution calling for Americans to be allowed to buy cheaper prescription drugs from Canada.

A month later he joined Sanders and Pennsylvania Democratic Sen. Bob Casey in introducing a bill that would accomplish the same goal of allowing Canadian drug imports and lowering costs. That bill addressed what Booker said was his problem with the resolution: the safety of the imported drugs.

But Booker was clearly stung by backlash from the left over his initial vote.

"When you're operating at this level, there are people who are really invested in pushing out fake stories, telling lies and half-truths in order to try take people down," he said. "I feel not only vindicated that we now have a strong piece of legislation that can probably get bipartisan support and actually get passed. But the cascading, untrue attacks definitely shows me the kind of climate that we're in, and how nefarious forces are going to try to spread lies and half-truths about you."

Since then, Booker has also sworn off corporate campaign contributions, a move Gillibrand, Harris and others have also made ahead of potential 2020 runs.

"I think one of the reasons why we're only one of six United States senators to not say we're not taking corporate contributions is to try to divorce ourselves from anybody's skepticism, as well as, being the change you want to see in the world," Booker said.

"I want to be able to make a difference on these issues without people being skeptical, because they're tying contributions -- which have never, never affected the way I decide on issues. ... I think that we were moving in that direction before this whole thing to say 'no corporate contributions whatsoever,' which we've done. Again, we are an early mover, and I bet you that we'll see more people follow over time."