Sen. Bernie Sanders, I-Vt., is returning to the campaign trail, but this time it will be to stump for his chief Democratic primary rival, presidential nominee Hillary Clinton.

The senator plans to make his return to campaigning sometime after Labor Day, he revealed in an interview.

"I look forward to it," he said. "I feel very strongly that Donald Trump would be a disaster for the country. I want to do everything I can to see that Secretary Clinton wins."

The senator is expected to stump for the Democratic candidate in quite a few states, including New Hampshire, Maine, Michigan Wisconsin, Ohio, Pennsylvania and Nevada, the Washington Post reported.

Sanders added he'll also be campaigning for Democratic candidates, including Katie McGinty in Pennsylvania, Ted Strickland in Ohio and Maggie Hassan in New Hampshire.

"I think we can create large turnouts," he said, explaining he expects to draw his usual numbers for rallies.

Though Sanders endorsed Clinton at the Democratic National Convention in Philadelphia last month, the relationship between the two camps has not been smooth.

Clinton's team reportedly expected to coast through the primary, and they weren't expecting any real opposition. Sanders proved them wrong, much to their chagrin.

The tenor of the Democratic primary turned increasingly bitter and personal as Sanders proved a formidable opponent for the former secretary of state.

Things were further complicated last month after a trove of hacked emails revealed a Democratic National Committee staffer actively pushed to see Clinton nominated and worked to thwart Sanders' election efforts.

One set of emails showed DNC staffers conspiring to undermine Sanders by questioning his religion.

The former director of Faith Outreach for the Democratic Party said he absolutely condemned the strategy.

"I can certainly say from first-hand experience that I was part of a campaign where it was a solemn vow in no way, shape or form to use faith as a wedge issue," Rev. Dr. Derrick Harkins, who also served as an adviser to President Obama, told the Washington Examiner.