MANCHESTER, N.H. — Three months ago, on a Monday night in New York, Robby Mook briefed a room full of donors and fundraisers on the progress of the campaign. Things back then were looking better. The summer was over and the email scandal was fading. There was the first debate and the Benghazi hearing and the feeling that momentum might finally be back on the side of Hillary Clinton.

Mook, her campaign manager, laid out a confident view of the next few months.

The primary, he told supporters at the November briefing, according to one attendee, would effectively be over by the end of March. (The 28 contests that month, Mook noted, would decide around 56% of delegates.) In this best-case scenario, he said, the campaign could spend April throughJune framing the general election and defining the Republican best positioned to win the nomination.

Now, after a one-point win in Iowa and a double-digit loss in New Hampshire, the trajectory Mook charted three months ago no longer seems like a given.

When polls closed here on Tuesday night, before Clinton greeted a crowd in the athletic center at Southern New Hampshire University, Mook released a strategy memo headlined "March Matters" that still predicted a "potentially insurmountable" lead by the end of that month — but also signaled at a long road ahead.

And an hour later, on stage beside her husband and daughter, the candidate did the same. "Here’s what we’re going to do. We take this campaign to the entire country," Clinton told supporters. "We’re going to fight for