Story highlights Sanders could join Hillary Clinton next week

A party platform meeting could determine if Sanders will back Clinton

(CNN) Bernie Sanders is poised to endorse Hillary Clinton at a campaign event Tuesday in New Hampshire, provided that final disagreements in the Democratic platform can be resolved during a weekend party meeting in Orlando, people familiar with the talks say.

For three weeks, Sanders has been steadily walking closer to throwing his full support behind Clinton, but has been withholding a formal endorsement until the platform is written. He repeated his pledge to help defeat Donald Trump again Thursday in an interview with Bloomberg View's Al Hunt.

"We have got to do everything that we can to defeat Donald Trump and elect Hillary Clinton," Sanders said. "I don't honestly know how we would survive four years of a Donald Trump as president."

Sanders has been seeking policy concessions from Clinton on college tuition -- which happened Wednesday, as Clinton rolled out a proposal to make tuition free at in-state public colleges and universities for those earning less than $125,000 per year for a family of four.

Also on Sanders' wish list: A commitment on health care to allow those aged 55 and older to buy into Medicare, and concessions in the Democratic platform to oppose the Trans-Pacific Partnership, a 12-country trade deal negotiated by President Barack Obama's administration, even in a lame-duck session of Congress before a new president is sworn in.

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