 -- A top Democratic senator said today many of the people President-elect Donald Trump has picked for top administration posts lack experience in the areas they would have to manage "in a very complicated world and a very complicated government."

"I call it the 3-G Cabinet — Goldman, generals and gazillionaires," Sen. Claire McCaskill of Missouri said today on ABC News' "This Week," referring to investment bank Goldman Sachs.

Asked by ABC News' George Stephanopoulos about ExxonMobil CEO Rex Tillerson emerging as a top contender for secretary of state, McCaskill said, "I worry about the lack of experience that he has had on the diplomatic front and, frankly, I think that's true for many of the appointments to Trump's cabinet. They haven't had experience in the areas that they're being asked to manage in a very complicated world and a very complicated government."

If nominated, Tillerson's relationship with Russian President Vladimir Putin may come under scrutiny. Tillerson was awarded Russia's highest civilian honor, the Order of Friendship, by Putin in 2013.

U.S. intelligence agencies have concluded that Russian actors engaged in hacking related to the U.S. election this year.

"This is a form of warfare for Vladimir Putin," said McCaskill referring to reports of Russian election interference. "Vladimir Putin - who is a thug and a bully and has friends around the globe who we don't want to be friends with - for him to be trying to impact our election, he has to be held accountable."

"I've had briefings just this last week that indicate that this is a very serious issue for the American people to understand," McCaskill said.

Among Trump's other choices for administration posts are Goldman executive Steve Mnuchin for treasury secretary and Steve Bannon, who worked at Goldman before becoming a conservative media executive, for chief strategist and senior counselor.

Trump has also named billionaire investor Wilbur Ross as his choice for commerce secretary and GOP donor and Michigan education activist Betsy DeVos for education secretary.

The president-elect has in addition named some former generals for his Cabinet, including retired Gen. James Mattis to lead the Pentagon and Gen. John Kelly, a retired four-star general and the former commander of U.S. Southern Command, to head the Department of Homeland Security.