He launched a successful, eight-day bus tour through rural Iowa last month that sparked an uptick in volunteers, precinct captain requests and caucus commitments. He increased his fundraising sharply in the last quarter, allowing him to flood the state’s airwaves with ads.

This week, Biden’s Iowa fortunes picked up again when he landed perhaps the most influential Iowa endorsement to date — Rep. Abby Finkenauer, the second youngest woman ever elected to Congress. That followed on the heels of endorsement from two other influential state Democrats — Tom Vilsack, a former governor and U.S. secretary of Agriculture, and his wife, Christie — and a well-timed cash infusion in TV ads from a pro-Biden superPAC.

Biden’s rebound comes amid a concentrated effort here. From Nov. 30 through this weekend, Biden will have spent 16 days in Iowa. By caucus day, he will have spent $4 million in integrated paid media, including broadcast TV, cable, Hulu, and social media.