A flight carrying Sen. Lindsey Graham from South Carolina to Washington made an emergency landing Monday afternoon after passengers noticed a strange noise coming from one of the plane's engines.

Graham, R-S.C., was on a plane that that was forced to return to Greenville-Spartanburg International Airport shortly after takeoff, Graham reported on Twitter.

"About 5 minutes into today's flight from Greenville to Washington, I and my other passengers noticed the engine making strange sound," Graham tweeted. "Not long afterwards, the pilot declared an emergency and we headed back to the airport. We safely returned with fire trucks and first responders at the ready."

Graham is running for re-election this year. The plane malfunction means he may not make it to the Senate in time for two critical votes Monday evening -- one on the confirmation of Janet Yellen to head the Federal Reserve and another to extend federal unemployment insurance benefits.