Sen. Bernie Sanders (I., Vt.) still wouldn't specify when he will be releasing his tax returns during an interview on Sunday, saying that he is still dotting the i's and crossing the t's.

Sanders appeared on CBS' Face the Nation, where he was asked by host Margaret Brennan whether he will be releasing his tax returns, noting that Sen. Kirsten Gillibrand (D., N.Y.) released some of her tax returns earlier in the week.

"We will. We have it all done. It's just a question of dotting the i's and crossing the t's," Sanders said. "Yes, we will, absolutely."

Brennan was about to ask a follow-up question, but Sanders interjected to shift the conversation to President Donald Trump.

"By the way, let me challenge President Trump to do the same,"Sanders said. "Trust me, we do not have investments in Russia or Saudi Arabia or any place else."

"Yes, we will be releasing them," Sanders repeated.

Sanders pledged during a Feb 25 CNN town hall that he would be releasing his taxes "sooner than later," but he has yet to release them, the Washington Free Beacon reported on Friday.