Former Massachusetts Gov. Mitt Romney won most of the delegates in the Oregon primary, leaving him 153 delegates shy of the number of delegates needed to win the Republican nomination for president.

He should get there by the end of the month.

Romney won at least 18 of the 25 delegates at stake in Oregon, with one delegate undecided as the vote count extended into Wednesday. Romney has a total of 991 convention delegates. It takes 1,144 delegates to win the GOP nomination.

All of Romney's challengers have stopped campaigning. However, Texas Rep. Ron Paul won at least three delegates, former Pennsylvania Sen. Rick Santorum won at least two and former House Speaker Newt Gingrich won at least one. Oregon awarded delegates in proportion to the statewide vote.

Romney also won the Nebraska presidential primary but no delegates were at stake.

Romney will have another chance to add to his delegate count next Tuesday, when a total of 75 delegates are at stake in primaries in Arkansas and Kentucky. If Romney continues to dominate the remaining contests, he is on pace to clinch the nomination May 29, when 152 delegates will be at stake in the Texas primary.