(CNN) House Democrats are sounding alarms that a prolonged fight for their party's presidential nomination will only serve to bolster President Donald Trump's reelection prospects, as many in their party grow anxious in the aftermath of his impeachment trial.

"I think Iowa made nobody happy -- everybody is ready to move on. New Hampshire is next week and we are moving forward," said Rep. Debbie Dingell, a Michigan Democrat. She added: "He can win again ... I've been saying it for a while."

"We shouldn't underestimate him," said Rep. Ro Khanna, a California Democrat and Bernie Sanders supporter. "Only eight American incumbent presidents have ever lost. It's always a challenge to defeat an American president. But he has a lot of glaring weaknesses."

While Democrats hope to exploit those weaknesses, they recognize that this week's events underscore the tall task ahead. The problems with the Iowa caucuses reinforced the belief that the party's nominating contest could last for months, and even extend to the Democratic National Convention in July without a clear winner.

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