WASHINGTON — Hillary Clinton may be the front-runner in the Democratic presidential nomination, but Bernie Sanders is running away with the race for campaign contributions.

For the third month in a row, the Vermont senator has taken in far more than Clinton, giving him the financial muscle to stay in the race through the Democratic convention in July.

On Monday, Clinton reported $29.5 million in donations in March — three days after Sanders announced a record $44 million haul.

Although Clinton has a large lead in delegates, Sanders’ has managed to pick up fund-raising steam from his network of small-dollar donors.

“He has the ability to be around for a long time,” said Lawrence Noble, general counsel at the Campaign Legal Center in Washington.

“What he has is a real base of small donors who are willing to give and willing to stay with him, and that is unique and unprecedented,” Noble told The Post. “What this shows is that the conventional wisdom that you cannot run a campaign on small donations is wrong.”

Clinton collects small contributions, too, but relies largely on big donors who can afford the $2,700 limit.