The margin of victory there was only about 1,500 votes, but a Sanders' spokesperson told CNN that he was ready to move on and "save the taxpayers of Missouri some money."
Clinton now leads Sanders among delegates 1,139 to 825. To win the nomination, a candidate must get 2,383 delegates.
The Washington Post reports that Sanders told supporters that he has "an extremely good chance" to win states such as Arizona, Idaho and Utah next week, and then carry that momentum to states such as California and New York.
Here are some recent tweets from the candidates:
I believe that morally and ethically we do not have a right to turn our backs on veterans who are sleeping out on the street.— Bernie Sanders (@BernieSanders) March 18, 2016
I want to end the sad reality of having more people in jail than any other country. I'd rather we have the best educated population.— Bernie Sanders (@BernieSanders) March 18, 2016
Sec. Clinton has a super PAC raising huge amounts of money from Wall Street and the fossil fuel industry. I am doing it a different way.— Bernie Sanders (@BernieSanders) March 17, 2016
It's 2016. Every student should have access to computer science classes.— Hillary Clinton (@HillaryClinton) March 17, 2016
Meanwhile, President Obama appears to be getting more involved in the race, telling donors that it's time to unite behind Clinton, the New York Times says.
Obama, however, has not given Clinton an endorsement publicaly or privately.
For more information on this year's race, visit the "Race for the White House" page on NBC12.com.