Vermont Sen. Bernie Sanders on Sunday blasted President-elect Donald Trump for his Cabinet picks thus far, saying it is shaping up to be a “Cabinet of billionaires.”

“I guess they have a few poor millionaires on it, but, mostly, it is billionaires,” Sanders told CBS’ “Face the Nation.” “And this is coming from a candidate for president, Mr. Trump, who told us he was going to take on the establishment. Well, maybe I am not seeing something here, but you don’t appoint the head of ExxonMobil to be secretary of state. That is not quite taking on the establishment.”

The net worth of Mr. Trump’s Cabinet selections thus far, according to estimates from Forbes and other outlets, is a combined $14 billion: several, including deputy commerce secretary pick Todd Ricketts, education secretary pick Betsy DeVos, commerce secretary Wilbur Ross and Small Business Administration pick Linda McMahon, are each worth more than $1 billion.

Sanders said there are “a lot of very important questions” Mr. Trump’s nominees need to be asked. That said, he added that he does not regret Democrats’ decision to implement the nuclear option -- even though it could help Mr. Trump pass his Cabinet nominees without the possibility of a filibuster in the Senate.

“We did that because Republicans were denying -- obstructing President Obama in every way, making it impossible to appoint federal judges, district judges, and really paralyzing the judiciary branch,” he said. “Many, many people there were not just getting the hearings they needed. We had to move forward.”

He called on Mr. Trump to publicly announce he would keep several of his campaign promises -- including avoiding cuts to entitlement programs and to reduce the price of prescription drug costs.

“He said: I, Donald Trump, am not going to cut Social Security. I’m not going to cut Medicare. I’m not going to cut Medicaid,” Sanders said. “And yet we are seeing Republicans in the Congress coming forward with devastating plans to cut Social Security, to cut Medicare. And I challenge Mr. Trump, today, tell the American people you are going to keep your campaign promises.”

Sanders also said the United States needs to take a “hard look” at Russia’s role in influencing the election, just days after multiple news reports confirmed that Russia was actively trying to promote Mr. Trump’s candidacy.

“I think when you have the intelligence agencies saying that that happened, when you have John McCain, when you have Democrats, when you have a bipartisan effort saying that we need an investigation, because this is very serious stuff, I think we go forward,” he said.

He said he was confused by Mr. Trump’s response to the reports.

“For Donald Trump to summarily dismiss all of this makes no sense to me at all,” Sanders said.

Sanders said the first step is to “get the facts,” which is what the bipartisan investigation is intended to do -- but also that the U.S needs to send a clear message to Russia that interference will not be tolerated.

“The word has got to go out to Russia, any other country on Earth, that we are going to protect our democracy, that cyber-security is very, very dangerous stuff, and we will not tolerate other countries interfering in the democratic process in this country,” he said.