The Iraq war is to blame for high gas prices as its cost has weakened the dollar and driven oil speculation, Sen. Claire McCaskillClaire McCaskillFive things to watch for in Mnuchin hearing Senators introduce dueling miners bills GOP must avoid Dems' mistakes when replacing ObamaCare MORE (D-Mo.), a national co-chair of Barack ObamaBarack ObamaReport: Manafort part of intelligence review of intercepted Russian communications Obama staffers challenged to WH scavenger hunt on final day Report: Trump has given up personal cellphone MORE's presidential campaign, said today.

"We cannot economically afford to keep borrowing two to three billion dollars a week from China," McCaskill said on MSNBC. "That's why gas prices are so high. People are speculating in commodities because nobody wants to go near our dollar. We cannot--it is unsustainable to continue to prop up, in the middle of a civil war, an Iraqi government that will not step up and do what they need to do."

McCaskill appeared on MSNBC this afternoon to discuss Obama's planned trip to Iraq and Afghanistan. McCaskill is a national co-chair of Obama's campaign. When host Monica Novotny pressed McCaskill on Obama's plan to withdraw from Iraq despite recent security gains, McCaskill pushed back by saying the war's cost is unsustainable.

"If you can't leave Iraq when it's stable and you can't leave Iraq when it's not stable, that means that we're stuck with George Bush and John McCainJohn McCainTillerson met with top State official: report McCain ‘very concerned’ about Tillerson US democracy is in crisis. Trump voters must help us get past it. MORE--we can never leave Iraq," McCaskill said. See the video below.