KANSAS CITY, Mo. — Vermont Sen. Bernie Sanders, one of the frontrunners in the race for the Democratic presidential nomination, has canceled a rally in Kansas City, Missouri, ahead of the Missouri primary.

Sanders had been scheduled to speak at an event at the Midland Theatre on Monday afternoon.

On Friday, his campaign said the senator had to cancel the Kansas City rally “due to scheduling constraints.”

Instead, he will host a Get Out the Vote rally at 11 a.m. Monday in St. Louis.

The other frontrunner in the Democratic race, former Vice President Joe Biden, is slated to be in Kansas City on Saturday afternoon . He will visit the National World War I Museum and Memorial at 4:15 p.m., where he is expected to “lay out his vision for America and listen to voters’ concerns.”

Biden will also visit St. Louis earlier in the day.

Missouri will be one of six states heading to the polls on Tuesday, one week after Super Tuesday results narrowed the Democratic field.

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