The Montana governor Steve Bullock has withdrawn from the race for the Democratic presidential nomination.

In a statement, he said: “While there were many obstacles we could not have anticipated when entering this race, it has become clear that in this moment, I won’t be able to break through to the top tier of this still-crowded field of candidates.”

Bullock entered the Democratic primary in May but never made a mark in polling. As of Monday morning, he was way off the pace nationally and in the latest polls in Iowa and New Hampshire, the states which vote first.

A spokeswoman told CNN: “Governor Bullock will continue to faithfully and effectively serve the people of Montana as their governor. While he plans to work hard to elect Democrats in the state and across the country in 2020, it will be in his capacity as a governor and a senior voice in the Democratic party – not as a candidate for US Senate.”

Thanking his campaign workers, Bullock said: “On the difficult days, I would joke, ‘It’s worth the sacrifice because it’s only a fair shot at the American dream and our representative democracy at stake.’ That truth remains.”

The Democratic field remains unwieldy, a host of candidates failing to register with voters. The realclearpolitics.com national average puts Joe Biden first on 27%, Bernie Sanders second with 18%, Elizabeth Warren third on 15% and Pete Buttigieg fourth with 11%.

Buttigieg has surged to lead in Iowa and New Hampshire. Warren has seen her momentum stall.

In the realclearpolitics.com national average, there is an eight-point drop-off after Buttigieg to the California senator Kamela Harris, whose failure to break through was the subject of an excoriating report in the New York Times over the Thanksgiving break.