WASHINGTON -- He presided over some of New Jersey’s first same-sex marriages. He was a leader in the push to ease sentences for low-level drug offenders and has amassed a liberal voting record on nearly every major issue. And he tirelessly campaigned for fellow Democrats in 2016 and 2018.

Yet as Sen. Cory Booker prepares to jump into the Democratic presidential race, some liberals still don’t trust him.

“For the most part he votes the right way. He really went out there in 2018, went above and beyond,” said Rebecca Katz, a progressive political strategist based in New York. “But I do think progressives are wary of his record.”

Liberals have long questioned Booker’s ties to wealthy interests, including Wall Street, Silicon Valley, and pharmaceutical companies; his coziness with former Gov. Chris Christie, a Republican; and his advocacy for charter schools. Now, as Booker prepares to launch a 2020 presidential campaign in the coming weeks, those issues could weigh on him as he competes with an array of contenders, including liberal champions such as Sens. Elizabeth Warren and, likely, Bernie Sanders.

But the long-standing questions about Booker also arrive with some new context, after six years in the Senate in which he has embraced many of the left’s most ambitious ideas, including Medicare for all, a federal jobs guarantee, and a proposal to give every newborn a taxpayer-funded savings account. Even some critics have taken note, though interviews suggest they are not entirely convinced.

"It’s nuanced, and I hope that comes through,” Katz said. “I do think he’s done a lot for the party, but I do think there’s reason for progressives to be skeptical.”

Recent straw polls by the liberal Daily Kos and MoveOn found Booker at or near the bottom of the pack among big-name Democratic contenders, garnering less than 3 percent support. In MoveOn’s December survey he was even a step behind former New York Mayor Michael Bloomberg, a onetime Republican.

Few doubt that Booker supports liberal causes. But some progressives wonder if Booker is truly a progressive crusader at heart, or if he is just following where others, like Sanders and Warren, have led.

“Sen. Booker has admirably been proactive in making progress on issues related to big pharma and Wall Street,” said Adam Green, cofounder of the Progressive Change Campaign Committee, which has supported Warren. But, Green added, “I think voters will want to not just know [candidates'] on-paper positions, but also understand their worldview enough to reliably predict their positions on future unanticipated issues.”

Other Democrats also face a reckoning over past stances.

Former Vice President Joe Biden recently admitted “it was a big mistake” when he backed a 1994 crime bill now blamed for mass incarceration. Sen. Kamala Harris (D., Calif.) has taken heat over her work as a prosecutor. And Sen. Kirsten Gillibrand (D., N.Y.) is answering for past stands on illegal immigration and guns.

“Many of the candidates that are going to announce are going to be tested and they’re going to have to answer for their record," said Karine Jean-Pierre, of the grassroots liberal group MoveOn. “We have moved as a party and as a country."

A Booker spokesperson pointed to his work to help boost economic opportunities in Newark, build new parks, and increase access to affordable housing, along with Senate initiatives on jobs, the environment, economic inequality, and prescription-drug costs.

“Senator Booker’s progressive record is unimpeachable,” Kristin Lynch wrote in an email. “He has put forward groundbreaking proposals that have driven the national progressive agenda forward.”

It’s unclear whether the skepticism about Booker is far-reaching, or limited to a vocal minority. He easily won a 2013 Democratic primary against three credible opponents, including two congressmen who had campaigned as liberal fighters. Democrats across the country have called on him to fly in and rally their supporters — suggesting that they see only upside in standing alongside the New Jerseyan.

But for some grassroots skeptics, suspicions about Booker crystallized during the 2012 presidential campaign, when, on NBC’s Meet the Press he condemned Democratic attacks on Bain Capital, the firm once run by then-GOP nominee Mitt Romney.

“This kind of stuff is nauseating to me on both sides. It’s nauseating to the American public. Enough is enough. Stop attacking private equity, stop attacking Jeremiah Wright,” Booker said, referring to Barack Obama’s former pastor. "This stuff has got to stop, because what it does is it undermines, to me, what this country should be focused on. It’s a distraction from the real issues.”

Critics still fume at that defense of private equity firms, while Booker allies say he was making a broader point.

Another flash point comes from Booker’s work with Christie to reshape public education in Newark by vastly expanding charter schools, backed by a $100 million gift from Facebook founder Mark Zuckerberg.

Booker allies say he was making a bold move to help at-risk children in failing schools — a cause liberals should support. But many on the left believe charter schools undermine traditional public education, and reporters who analyzed school budgets found that much of the money went to consultants, not teachers.

“Education-wise, he’s not far removed from a Betsy DeVos philosophically,” said John Abeigon, president of the Newark Teachers Union, referring to President Donald Trump’s education secretary. “It’s sad because we support him on most issues. But that’s a major issue.”

Booker served on the board of DeVos’ Alliance for School Choice, which advocated public money for charter, private, and religious schools.

Booker aides point to a Harvard study that found that after initial declines in achievement, Newark students had improved significantly in English, though not math. Most of the gains happened after Booker had left the mayor’s office and moved to the Senate.

Booker’s significant fund-raising from people who work on Wall Street or at major pharmaceutical companies, both major employers for New Jerseyans, has also fueled liberal concern. The Wall Street Journal recently reported that of all the major Democratic contenders for 2020, Booker has relied most heavily on those who can write massive checks rather than everyday people who give $20 or $30 at a time.

Booker supporters bristle at questions about his core beliefs. They point out that after graduating from Stanford, Yale Law, and Oxford he moved into a Newark housing project to work on the difficult issues in a city racked by crime and poverty.

They draw a distinction between him and DeVos by noting that the Newark charter schools remained public, not the private schools she favors. And they point out that he spoke out against DeVos' confirmation. The New Jersey Education Association, the statewide teachers' union, endorsed Booker in 2014.

“On the core issues like LGBT, abortion, and marijuana reform and criminal justice reform, he’s like A-plus-plus-plus-plus-plus,” said Jay Lassiter, a liberal activist from Cherry Hill who supported Sanders in 2016.

Booker has used his fame to lead a rally on the Capitol steps to support the Affordable Care Act and help organize a filibuster for tougher gun laws. In 2017 he testified against then-Attorney General nominee Jeff Sessions, breaking Senate protocol by speaking out against a colleague.

But two days later, Booker opposed a Sanders proposal to allow the importation of prescription drugs from Canada. It was a symbolic, nonbinding vote, but liberals were outraged, again concluding that Booker had sided with moneyed interests.

Booker said he had concerns about the plan’s safety controls. Since then, he and Sanders have teamed up on several bills to lower drug costs. They introduced their latest earlier this month, with Booker standing next to his potential 2020 rival.