With less than a week to go before the Wisconsin primary, a new poll shows Democratic presidential hopeful Bernie Sanders harnessing his post-weekend momentum into a widening edge over rival Hillary Clinton.

The Marquette Law School poll (pdf) published Wednesday shows Sanders leading Clinton, 49 to 45 percent.

In the February version of the same poll, Sanders led Clinton 44 percent to 43 percent. According to the Wisconsin State Journal, "Clinton has been steadily losing ground to Sanders over the course of several Marquette polls dating back over the past year."

Wisconsin's open primary will be held Tuesday, April 5, and with 96 proportionally allocated delegates at stake, it's "a must-win for Sanders," as The Hill put it. 

The Marquette poll surveyed 405 likely Democratic voters March 24–28. Its margin of error is 6.3 percentage points.

While Sanders was in Madison on Wednesday for several appearances including a town hall meeting, Clinton was scheduled to be in New York City at a fundraiser hosted by former Morgan Stanley Chief Financial Officer Ruth Porat.

Sanders' campaign manager, Jeff Weaver, noted the candidates' divergent approaches in an email to supporters on Wednesday. "Hillary Clinton left the campaign trail for yet another high-dollar fundraising event on Monday," he wrote, "but she shared some news about the state of the race that we agree with: she said the trail to the Democratic nomination 'goes through Wisconsin.'"