Likely 2020 Democratic presidential candidate Julian Castro agrees with Rep. Alexandria Ocasio-Cortez that tax rates on some of the wealthiest Americans should skyrocket.

"Oh, I can support folks at the top paying their fair share," Castro told ABC News' "This Week" on Sunday when asked directly whether he could endorse the high-profile New York Democrat's idea.

The Obama-era Housing and Urban Development secretary, who is expected to officially announce he's running for the White House this week, made the comments after Ocasio-Cortez, D-N.Y., caught flak for suggesting people earning more than $10 million could be taxed between "60 or 70 percent."

In offering support to Ocasio-Cortez, Castro provided historical context given the current highest marginal income tax bracket is 37 percent for those receiving more than $500,000 a year.

"There was a time in this country where the top marginal tax rate was over 90 percent, even during Reagan's era in the 1980s it was around 50 percent" the former mayor of San Antonio, Texas, said.

Castro also floated "that we get more serious about making sure the corporations pay their fair share," so the country can fund policy programs like "Medicare-for-All," as well as universal pre-kindergarten and higher education.

"During this campaign, if I run, I'm going to be very up front with the American people on how we would do that because I think that they are owed that, but it is worth it. It is worth it in this country for us to do that," he said, vowing not to be "a single issue candidate."

Castro additionally responded to criticism he didn't have the foreign policy experience to be the next occupant of the Oval Office. He said his time serving in former President Barack Obama's Cabinet and as San Antonio's mayor "certainly qualifies one to be commander in chief." Last month Castro said he believed U.S. troops should be pulled from Syria though he would have handled the situation differently to President Trump.

Castro formed a presidential exploratory committee in December. He is scheduled to hold a press conference to discuss his 2020 plans on Jan. 12.

[Opinion: Alexandria Ocasio-Cortez and Tucker Carlson have one thing in common: Flimsy tax arguments]