The Vermont senator will blanket the airwaves for the next 10 days with about 1,900 ads air in Denver, Colorado Springs and Grand Junction. The campaign will shell out more than $670,000, according to public filings.
Sanders is locked in a primary battle with Hillary Clinton. And Colorado is seen by some local political consultants as a state where Sanders can capture a victory on March 1, Super Tuesday.
Sanders has dominated among young, independent voters in New Hampshire and Iowa.
The Clinton campaign says it has 30-second spots running on cable and broadcast outlets in the Denver area.