Sen. Ted Cruz (R-Texas) scored a victory in the Idaho Republican primary on Tuesday, adding strength to his argument that he's the candidate to defeat Donald Trump.

Cruz's win in Idaho comes off his strong showing on Saturday, where he won two states -- Kansas and Maine -- and came closer than expected to Trump in Louisiana and Kentucky. 

Cruz supporters anticipated that Idaho could be a good state for him -- the senator has done well in rural states with smaller populations -- and he added a last-minute campaign event there over the weekend. Cruz has tended to do better in states whose contests are closed, meaning only registered Republicans can vote.

He and his campaign have focused intensively on grassroots, on-the-ground organizing -- a contrast to Trump, who relies on big flashy rallies to optimize media exposure. 

"Republicans have gotten away from running grassroots campaigns," Mark Campbell, Cruz's national political director, told The Huffington Post after the senator's win in Kansas Saturday. "We've worked exceptionally hard at it and are exceptionally proud of it." 

The other three candidates also all visited the state in the run-up to the primary. Sen. Marco Rubio (R-Fla.) had the backing of Sen. Jim Risch (R-Idaho), Ohio Gov. John Kasich (R) had Idaho Gov. Butch Otter's (R) support and Cruz nabbed the endorsement of Rep. Raul Labrador (R-Idaho).