SIOUX FALLS, S.D. (AP) — U.S. presidential hopeful Bernie Sanders is on a campaign swing through South Dakota.

The Democratic senator from Vermont scheduled rallies Thursday in Pine Ridge, Rapid City and Sioux Falls, less than a month before the state's presidential primary. Admission to each of the events is free and on a first come, first served basis.

Sanders is competing with Hillary Clinton for the Democratic endorsement. Whoever gets it likely will run against presumptive Republican nominee Donald Trump.

Sanders held rallies in Montana on Wednesday and has two events scheduled in North Dakota on Friday.