Duckworth was expected to capture the nomination with support from the Democratic establishment and significant leads in both polling and fundraising
Duckworth also defeated Illinois State Sen. Napoleon Harris.
Incumbent Sen. Mark Kirk also glided to victory on Tuesday night, winning the GOP nomination over little-known challenger James Marter.
Duckworth and Kirk will now go head-to-head in what is considered to be one of the most competitive and expensive Senate races this cycle.