Two people familiar with his decision say Scott Walker is dropping out of the Republican race for president.
The Wisconsin governor planned a news conference for Monday evening in Madison, where he was expected to become the second major GOP candidate to quit the race.
The people spoke on condition of anonymity because they were not authorized to speak before Walker's announcement.
Walker tried to capitalize on his record taking on unions and got off to a strong start after a well-received speech to Iowa conservatives in January, formally launching his campaign in July.
But the 47-year-old Walker fell after a series of stumbles on the campaign trail and forgettable performances in the early GOP debates.
Walker joins former Texas Gov. Rick Perry as two early 2016 dropouts.