CNN projected Santorum the winner in the non-binding vote at local caucuses held across the state. With 78 percent of the votes counted, Santorum, the former U.S. senator from Pennsylvania, had 40 percent (3,074) to 27 percent (2,101) for Paul, the libertarian-leaning congressman from Texas; 25 percent (1,935) for former Massachusetts Gov. Mitt Romney; and 8 percent (641) for former U.S. House Speaker Newt Gingrich of Georgia.
Paul had invested a good deal of time, energy and money in North Dakota, a sparsely populated state where political strategists said he stood a better chance of success through grass-roots campaigning.
North Dakota's 28 delegates will remain unbound until the party's state convention.