Photo

Senator Bernie Sanders of Vermont, energized by victories Saturday in Kansas and Nebraska, declared that people should not “write off” his campaign and that the caucus wins show that he has the momentum to gain the Democratic presidential nomination.

Mr. Sanders, in an interview from the hotel where he is staying in Detroit, said he won Kansas by a “pretty good margin” (indeed, it was 2-to-1) and that he expected to do well in contests in Maine, Michigan, California, New York, Oregon and Washington.

“We are having a very, very good weekend,” Mr. Sanders said. “We think we have a lot of momentum behind us as we continue forward.”

Still, Mrs. Clinton’s one victory Saturday, a nearly 50 percentage point romp in Louisiana, was enough to give her eight more delegates for the day than Mr. Sanders won, further extending her large lead in the race.

Some of that lead owes to superdelegates, Democratic Party leaders and elected officials who are overwhelmingly backing Mrs. Clinton, though they could still change their preference. Mr. Sanders called them “establishment people whose main concern is to defeat Republicans” and that those superdelegates will eventually back him if he keeps winning.

Mr. Sanders, who has lagged Mrs. Clinton among black and Latino voters, also said he believed he was having some success broadening his support. “We are losing badly among elderly whites, elderly blacks and elderly Latinos,” he said. “We are doing much, much better and in some cases winning among younger Latinos, younger blacks and certainly among younger whites. But I think we are gaining momentum within the Latino community and the African-American community. But we still have a long way to go.”

Mr. Sanders also expressed frustration as he explained that his campaign will go on.

“I don’t want to disturb the media narrative too much — don’t get people too upset, but don’t write us off,” Mr. Sanders said. “I think we have a path toward victory.”