Susan Page

USA TODAY

Vermont Sen. Bernie Sanders' campaign is braced for a tough night Super Tuesday.

It may be even tougher than they fear.

A new Suffolk University Poll of 500 likely Democratic primary voters in Massachusetts shows Hillary Clinton leading Sanders by eight percentage points, 50%-42%. The survey, which has a margin of error of plus or minus 4.4 points, was taken Thursday through Saturday — before Clinton's nearly 50-point landslide in South Carolina Saturday bolstered her momentum.

Analysis: Clinton rout in South Carolina puts her on path to nomination

Massachusetts and Oklahoma are Sanders' best hopes for a primary victory Tuesday outside his home state of Vermont, where he's expected to prevail. He also has focused on caucuses being held in Colorado and Minnesota. But failing to win the primary in the liberal-leaning Bay State, next door to Vermont, would raise questions about just where he could win additional primary contests.

That said, Sanders has significantly improved his standing since the previous Suffolk poll was released last November. Then, 30% of those surveyed supported the Vermont senator, compared with 54% for Clinton. But Clinton's lead in the new survey is the largest she's had among four public polls released over the past two weeks.

USA TODAY's 2016 Presidential Poll Tracker

"A large group of independents will have to decide whether to vote for Bernie Sanders in the Democratic primary or John Kasich in the Republican primary on Tuesday," said David Paleologos, director of the Political Research Center at Suffolk University, which is in Boston. "That decision will have a direct impact on both races."

Massachusetts holds an "open primary" that allows independents to vote in either party's contest.

Indeed, Kasich, the Republican governor of Ohio, is relatively popular even among likely Democratic primary voters in Massachusetts. Republican front-runner Donald Trump has a dismal favorable-unfavorable rating of 14%-77%, and Texas Sen. Ted Cruz of 9%-76%. But Kasich has a net positive rating, 42%-27%.

Among the Democrats, Clinton's favorable rating is 67%-23% and Sanders is even better, at 71%-16%.

Regardless of whom they support, most of those surveyed predict Clinton will be the next president: 51% chose her compared to just 12% for Sanders — and 16% for Trump.