By: Dan Roberts

Bernie Sanders will on Monday urge supporters to consider how “far superior” Hillary Clinton is to the alternative, as Democrats seek to defuse fresh outbreaks of tension at the start of their four-day national convention in Philadelphia.

In a crucial opening night address to delegates, the Vermont senator will appear alongside first lady Michelle Obama as the party seeks a display of unity in contrast with Republican infighting in Cleveland last week.

The star-studded convention got off to a rocky start on Sunday, when Democratic National Committee chair Debbie Wasserman Schultz was forced to announce her resignation on the eve of proceedings, following revelations of bias against Sanders during the long and bitter primary contest with Clinton.

But the Sanders campaign seemed keen to put the fight behind it over the weekend, despite the leaked emails which showed DNC staff sought to exploit his religious beliefs and Wasserman Schultz openly dismissing the notion that he could ever win.

“Sanders will make it clear that Hillary Clinton is by far superior to Donald Trump on every major issue from economics and health care to education and the environment,” said his spokesman Michael Briggs, in a statement before news of the Wasserman Schultz resignation.

In a surprisingly muted response to the resignation, Sanders said she had made the right decision but paid tribute to her “years of service”.

Despite tense relations between the campaigns during the primary fight, Sanders has swung rapidly behind team Clinton since a full-throated endorsement speech two weeks ago in New Hampshire, claiming he had moved the party’s nominee to the left in a series of negotiations over policy.

“Sanders will stress that the most progressive platform in Democratic Party history includes agreements he reached with Clinton to dramatically expand healthcare access and to make public colleges tuition-free for students from families with annual incomes up to $125,000 a year,” said Briggs, in a preview of the Monday night speech.

“In his remarks, Sanders also plans to rip into Trump for siding with the Koch brothers and echoing fossil fuel industry claims that climate change is a hoax despite the virtually-unanimous scientific consensus that the warming planet is causing devastating harm.”

Nevertheless, some Sanders supporters were in an angry mood over the DNC email revelations and there were an ambivalent atmosphere, at best, reigned over some events in Philadelphia on Sunday evening. Some activists planned demonstrations and sit-ins in the city, in protest against the party’s continued use of super-delegates in its nominating process.