Before this year, Massachusetts Senator Elizabeth Warren hadn't missed a roll call vote since 2014. But presidential candidates travel a lot, and since January, she been absent for 28% of votes, according to numbers on the website GovTrack.

That's about middle of the pack for the eight current members of Congress still in the presidential race, all of whom are Democrats. Senator Bernie Sanders of Vermont has missed 40% of votes.

Warren’s campaign and Senate offices, contacted last Thursday, have not yet offered a comment on the missed votes.

Sanders's campaign manager, Faiz Shakir, said in a statement the senator has made a commitment to try to win the presidency.

“He's all in," Shakir said. "That sometimes comes at the expense of missing a few Senate votes, but if there are ever any votes that hinge on his presence, he will certainly be there."

And it’s true that none of the votes Sanders or Warren missed were so close that a single senator could have changed the outcome.

Congressman Jim McGovern of Worcester, who has endorsed Warren for president, is unconcerned.

"In terms of protecting the interests of Massachusetts, and being there on the important issues, Elizabeth Warren always shows up," McGovern said in an interview in July. "So I'm willing to cut her a little slack, because I think she's a great United States senator and I think she'll be a great president."

During his campaign for president a dozen years ago, then-Senator Barack Obama missed 46% of Senate roll call votes. His absence rate was 38% during the first year of his campaign — 2007, but jumped to 64% in 2008.

Adam Frenier contributed to this story, which comes from the New England News Collaborative, eight public media companies, including The Public's Radio, coming together to tell the story of a changing region, with support from the Corporation for Public Broadcasting.