Heidi M. Przybyla

USA TODAY

Hillary Clinton may be headed for another loss in a Democratic primary battle she thinks she’s already won.

Following his win in Indiana a week ago, Tuesday’s contest in West Virginia is part of a pocket of states voting this month, such as Oregon, where Bernie Sanders is expected to do well — even after Clinton carried a number of Eastern states in April that put her on a path to clinch the nomination.

Clinton, appearing Sunday on CBS’s Face the Nation, continued to nudge the Vermont senator to get behind her campaign, citing her own experience rallying behind Barack Obama in 2008 when the popular vote and delegate count were tighter. Heading into Tuesday's contest, Clinton leads Sanders by more than 3 million popular votes and nearly 300 pledged delegates.

“He has to make up his own mind,” said Clinton. “I want to unify the party. I see a great role and opportunity for him and his supporters to be part of that unified party,” said Clinton.

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A RealClearPolitics polling average gives Sanders a 6-point lead over Clinton in West Virginia, though that's based on a limited number of surveys. In a rally Sunday night in Piscataway, N.J., Sanders pledged to continue campaigning until the final voting in the District of Columbia on June 14. “We are gonna fight for every single vote,” Sanders said.

On CBS, Clinton made clear her chief target is presumptive Republican nominee Donald Trump, repeatedly referring to him as a “loose cannon.”

West Virginia, one of the states hardest hit by a decline in the coal industry and manufacturing jobs losses, exemplifies her challenges in framing her economic populism message against Trump. Last week, Clinton took a tour of Appalachian communities across Kentucky, West Virginia and Southeastern Ohio.

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“The state’s becoming increasingly conservative” amid a downturn in the coal industry, said Carte Goodwin, a West Virginia attorney who briefly served as a U.S. senator after the death of longtime Democratic Sen. Robert Byrd. A recent Public Policy Polling survey gives Trump a 27-point lead over Clinton in the state.

Trump hopes to replicate his strength among white working-class voters in other industrial Rust Belt states like Pennsylvania and Michigan, where polls currently give Clinton the advantage and which have favored Democratic presidential candidates in recent elections.

Even if Sanders carries West Virginia, he’d have to win by a big margin and repeat that performance in every remaining contest in order to close in on Clinton’s delegate lead. Democrats reward their delegates on a proportional basis, so just winning a state isn’t enough. In the final delegate-rich prize of California, with 475 pledged delegates at stake, Clinton is ahead by an average of ten points.

West Virginia is representative of Clinton’s strategic challenge in the general election against Trump.

While Clinton has solid support among minorities in lower-income brackets, working-class whites have been drawn to the New York real estate mogul.

Clinton spent much of her tour last week apologizing for earlier comments suggesting she wanted to put the coal industry out of business. ”Some of the comments Secretary Clinton made earlier in the year concerned people, rightfully so,” said Goodwin.

On Monday, ahead of the West Virginia primary, Clinton was in northern Virginia trying to capitalize on Trump’s negative ratings among female voters.

Clinton scheduled a discussion with women in Loudoun County about work-life-balance issues, including paid leave and affordable child care as she attempts to reach independent and Republican women who are averse to voting for Trump.

Loudoun County is one of the suburban Virginia swing counties that’s been a good gauge of presidential winners, having backed both President Obama and President George W. Bush.