At some point in the past few years, Sen. Elizabeth Warren got religion on interns.

In 2014 and 2015, the Massachusetts Democrat paid a handful of interns a couple thousand dollars each, totaling less than $50,000 in payments to interns in the two years combined. The vast majority of her interns — usually about 100 per year — were unpaid.

But last spring and summer, Warren became the single most generous intern employer in the U.S. Congress, paying out about $225,000 to 54 interns for the fiscal year that ran from Oct. 1, 2017 to Sept. 30, 2018, according to Senate expenditure records analyzed by the New England Center for Investigative Reporting. Sen. Susan Collins of Maine spent $209,000 on interns during the same period; Sen. Bernie Sanders of Vermont spent $201,000. Nobody else in the Senate came anywhere close.

Approximate spending of each US Senator on paid interns in fiscal year 2018 (Oct. 1 2017-Sept. 30 2018), as published in the U.S. Secretary of the Senate’s semi-annual spending reports. Chart controls allow you to see which Senators also spent $0-25k on interns during the same time period.

Only three other senators spent more than $100,000 on interns, and most of the senators who paid some interns spent somewhere between $25,000 and $50,000 for the year. Around 40 senators — including Massachusetts' other Democratic senator, Ed Markey — reported no paychecks to interns at all for the year. The interns worked for free, or got funding elsewhere.

Sanders and Collins have long been top intern spenders, both paying out more than $140,000 in fiscal years 2017 and 2016 as well. But Warren is a newcomer to these top ranks. In fiscal year 2016 she spent about $46,000 on interns. A year later, her total was up to $89,000. And then last year, her intern spending nearly tripled.

“Our office is proud to give students from a diverse set of backgrounds the opportunity to work in public service,” said Warren’s digital press secretary, Alexis Krieg. “Paying interns adequately is a values-based priority that Sen. Warren takes seriously, and over the course of her first term in office we’ve worked to ensure our policies and budget reflect that.”

The number of interns in Warren’s office apparently hasn’t changed. What has changed is that now Warren is aiming to pay more of them and raised her rate to $15 an hour for interns who are not being funded by their schools or some other program.

Markey has apparently also begun paying interns, though those pay records won’t be public for several months. “It’s important to offer all students the opportunity to be fully immersed in the legislative process,” Markey said in a statement. “My office values diversity, and it’s important to me that we engage with applicants who would not have the opportunity to serve in our congressional office without financial support.” He did not explain why he did not pay interns in prior years.

Each member of Congress is given a taxpayer-funded budget to pay for staff, office supplies, travel and other official activities, but they cannot use this money for political activities. Under pressure from grassroots activists, Congress late last year approved an extra $14 million for congressional offices to pay interns, with a budget for each office based on the size of the state. Under that legislation, Warren and Markey are each getting an additional $48,700 this year to pay interns.

Overall, Republican Senators paid their interns about $1.7 million in fiscal year 2018, nearly double what Democratic Senators paid their interns.

Intern Expenditures by Senators

“The fact that you have these people paying interns is a great thing," said Meredith McGehee, a congressional ethics expert. "It’s really good that it’s happening.”

But McGehee — the executive director of a group called Issue One that works to reduce the influence of money in politics — cautions that it is also important to ensure that “senators are staffed by qualified professional staff because that's the best way to ensure we get the best policy.” Warren had a dramatic increase in intern salaries in 2018. “If that money went to the internship program, where was that money going before?” asked McGehee.

During the same period last year that Warren was increasing her pay to interns, a half dozen professional staff members left her office to work for her re-election campaign or other political operations. But her office says there was no connection between those two things, and interns were not being used to replace professional staff.

“Interns perform an important role in our office, but they are never used as substitutes for professional staff,” Krieg said.

Guillermo Creamer Jr., co-founder and deputy director of the grassroots group Pay Our Interns, said he was surprised to learn Warren had been so generous with intern salaries because her office did not work with his group when it was pushing for the intern pay legislation last year.

“We did reach out to Sen. Warren's office [but] there was a lack of transparency,” Creamer said. “They did not want to meet in person to talk about the details of their internship program. … We knew that she was offering some type of compensation but we didn't know exactly what was going on.”

Creamer noted that the internship application on Warren’s Senate website made no reference to available subsidies or pay, which could discourage lower income students from applying.

Markey’s site, by contrast, declares in bold letters, “Paid internships are awarded to low income students or to those who may not otherwise be able to afford to live or work” in either Boston or Washington, D.C. The office invites applicants to submit a letter explaining the financial hurdles they face, which is reviewed separately from the internship application.

In response to Creamer's criticism, Warren's office added a line to its website last week, saying, “Our office offers paid internships to accepted applicants who will not receive funding through their college/university or an outside program.”

Creamer says his group would love to hold Warren up as an example for other political offices. “I think it's very important for someone who is in such a prominent position, who is going to run for president, to highlight this,” he said. “If she becomes a candidate who signs on to our pledge saying that she's going to pay her interns on the campaign trail the same way she's paying her interns in the Senate office, that's huge. You know that is something to be proud of.”

New England Center for Investigative Reporting interns Bryn Seltzer and Sophia Brown contributed to this story.