Story highlights Bernie Sanders is stumping hard for Hillary Clinton

He says beating Donald Trump is the highest priority

Lebanon, New Hampshire (CNN) After a bitter primary battle, Bernie Sanders stood on Monday on a stage flanked by signs that read "Stronger Together" and his message was clear: Democrats must elect Hillary Clinton because Donald Trump has "no core set of values."

The Vermont senator took to the trail on Labor Day for the first time stumping by himself to support Clinton. He was in familiar territory in New Hampshire, where he's practically embraced as a native son and won a rousing primary victory early in the year.

In the waning summer warmth, Sanders spoke at the Clinton campaign organized event, making him one of many surrogates out on the trail on Labor Day for the Democratic nominee, including Vice President Biden and former president Bill Clinton.

The senator spoke to a crowd of several hundred, weaving his stump speech at the beginning into a compare and contrast list of what makes Hillary a better candidate than Trump. He spoke some about his primary campaign and thanked New Hampshire voters for their support during the primary, and broached his favorite issues of affordable college tuition, striking down Citizen's United, and income inequality.

"What are the important issues facing America and what are the positions of the candidates on those issues?... The answer is 100% clear that on every issue Hillary Clinton is the superior candidate hands down," Sanders said to a crowd holding "NH" signs.

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