CAMBRIDGE, Mass. (AP) -- Sen. Elizabeth Warren is quickly becoming a top Democratic fundraiser and campaign powerhouse, hitting the road on behalf of candidates in key races the party will need to win to retain control of the U.S. Senate in November.
Since March, the Massachusetts Democrat has stumped for candidates in Ohio, Minnesota, Oregon, Washington and Kentucky and has trips planned this week for West Virginia and Michigan. It's a hefty schedule for a freshman senator who not long ago was teaching law at Harvard.
Along the way, Warren has found her brand of economic populism resonating far from her home in the liberal enclave of Cambridge, Massachusetts.
Part of Warren's economic pitch is legislation she sponsored that would let college graduates refinance their student loans at lower interest rates, an effort blocked by Senate Republicans.
Warren found a receptive crowd during a recent campaign stop at the University of Louisville with Alison Lundergan Grimes, the Kentucky secretary of state hoping to unseat Senate Republican Leader Mitch McConnell.
Warren said the Kentucky race is "about a man who stood up and filibustered the student loan bill."
"When you've got a choice between billionaires and students, Mitch McConnell says it is more important to protect the billionaires," Warren told the crowd. Senate Republicans blocked Warren's student bill last month on a 56-38 vote that fell short of the 60 needed to advance the proposal to a debate.
McConnell's campaign spokeswoman Allison Moore was quick to highlight Warren's awkward fit in coal country, noting that she supports the federal government's efforts to restrict carbon dioxide emissions, restrictions many in Kentucky oppose.
McConnell had criticized Warren's bill when it came up for a vote, saying it won't make college more affordable or reduce the amount of money students will have to borrow.
"The Senate Democrats' bill isn't really about students at all. It's really all about Senate Democrats," he said. "They want an issue to campaign on to save their own hides this November."
Cast by critics as a typical Northeast liberal, Warren, 65, grew up in Oklahoma in a family which she said lived on "the ragged edge of the middle class" -- an experience that she said helped forge a lifelong interest in advocating for working families trying to get a fair deal in an economic and political system that Warren argues is rigged against them.
Warren found herself thrust into the national political spotlight during a grueling 2012 campaign against incumbent Republican Sen. Scott Brown. It was the most expensive campaign in Massachusetts history with both candidates raking in tens of millions in donations.
Warren's profile has made her a go-to campaigner for Democratic Senate candidates, in part because as a newer arrival on the political stage she is free of some of the political albatrosses carried by other top Democrats like President Barack Obama or Hillary Clinton.
In March, Warren attended a fundraising reception and dinner in Cleveland for Ohio Sen. Sherrod Brown. Days later she attended a student rally and fundraiser for Minnesota Sen. Al Franken in Minneapolis. Next were fundraisers in May for Oregon Sen. Jeff Merkley and Washington Sen. Patty Murray.
Now, Warren is continuing her fundraising efforts, with a planned Monday event with West Virginia Democratic Senate hopeful Natalie Tennant. Tennant, West Virginia's secretary of state, is vying with U.S. Rep. Shelley Moore Capito for the seat held by retiring Democratic Sen. Jay Rockefeller. Capito is favored and holds a hefty cash advantage.
Capito's campaign has also been quick to target Warren, calling her "one of the staunchest opponents of coal and West Virginia's way of life."
Warren has conceded that she and Tennant -- who, like Grimes, has criticized Obama's plans to limit carbon emissions from the coal industry -- don't agree on everything, but can come together on economic issues facing struggling families.
Later in the week, Warren is scheduled to attend a fundraiser with Michigan Democratic Senate hopeful Gary Peters who is facing off against Republican Terri Lynn Land. Peters and Land are competing to replace Democratic Sen. Carl Levin, who's also retiring.
Warren has also sent out fundraising emails to her supporters on behalf of Democratic Senate candidates in Georgia (Michelle Nunn), South Dakota (Rick Weiland) and Iowa (Bruce Braley).
Warren's rising political star in the Democratic Party has garnered the attention of Hillary Clinton, in part because Warren has been seen by some as a possible alternative candidate for president in two years, even though Clinton has yet to announce and Warren has repeatedly said she's not interested in running in 2016.