WASHINGTON — Bernie Sanders, his momentum slowed by a loss to Hillary Clinton in Nevada, faces two tests in the weeks ahead: parceling out his formidable resources to the states that offer his best targets, and boosting turnout in what thus far has been a mediocre year for it.

His path to the Democratic nomination, already steep, has narrowed considerably now that Clinton has reestablished herself as the front-runner. To win the nomination, Sanders acknowledged Sunday, he will have to begin winning again, as he did when he trounced Clinton in New Hampshire.

‘‘We’re studying that issue very closely, obviously, as to where we allocate our resources and allocate my time,’’ Sanders said.

Though Sanders campaigned in South Carolina on Sunday, Clinton is a heavy favorite there. Then the campaign moves into a trove of diverse, delegate-rich southern states that are also considered favorable terrain for Clinton.

Sanders has the ability to remain in the race for the distance, thanks to his fund-raising, and to the Democrats’ system of allocating delegates proportionally rather than in a winner-take-all fashion.

In Nevada, for example, Sanders lost to the former secretary of state by more than five percentage points but still came away with almost as many delegates as she did, taking 15 to her 19.

‘‘We are in this race to the convention,’’ Sanders said Sunday on NBC’s ‘‘Meet the Press.’’ ‘‘I think we’ve got some states coming down the pike that we’re going to do very, very well in. . . . If you look at national polling, our support is growing.’’

He ticked off five Super Tuesday states in which he said he has ‘‘a good shot’’ on March 1: Colorado, Massachusetts, Minnesota, Oklahoma, and his home state of Vermont.

Colorado and Minnesota both choose their delegates in caucuses. The caucus system, which generally brings out only the most motivated activists, presumably makes them friendlier to a candidate such as Sanders, who has inspired liberal Democrats.

But caucuses require a bigger investment of time, making it harder to draw out less committed voters, which could give Sanders a disadvantage.

One line of thinking within the campaign, for example, is that he would have won Nevada had it been a primary instead of a caucus. And in fact, turnout was not down in New Hampshire, the only primary to be held so far.

In 2008, Barack Obama caught Clinton’s presidential campaign off balance by running up its delegate totals in caucus states — a mistake that Clinton’s team has vowed it will not repeat. She has won the first two caucus states, Iowa and Nevada. And her Colorado and Minnesota operations have been up and running since last fall.

Sanders strategist Tad Devine said the senator is likely to mount a strong primary challenge to Clinton in Kansas and Nebraska, both of them likely to go into the Republican column in November.

More recently, Sanders and his strategists have begun talking up their chances in Michigan, which holds its primary on March 8. Both the Sanders and Clinton campaigns last week began airing their first television ads.

‘‘We can have a big showdown in Michigan,’’ Devine said. ‘‘If we can beat her in Michigan, I think we can go into March 15 with a lot of momentum.’’ On that date, five states vote.

One area where Sanders acknowledged he must do better is in voter turnout. The constituencies he does best with — especially young people — are notoriously difficult to draw to the polls.

And in the caucuses so far, overall numbers of Democratic voters showing up have been nowhere near the levels they were in 2008, the last time there was a contested nomination.

In Nevada, about 80,000 turned out for the caucuses, compared with nearly 118,000 in 2008, state Democratic party officials estimated.

‘‘What I’ve said over and over again, we will do well when young people, when working-class people come out,’’ Sanders said in his NBC interview. ‘‘We do not do well when the voter turnout is not large. We did not do as good a job as I had wanted to bring out a large turnout.’’