Todd Blanche’s nomination to be President Donald Trump’s attorney general is hanging in the balance with a key GOP senator saying the Justice Department has not done enough to assure him a controversial $1.8 billion “anti-weaponization” fund won’t move forward.

The pushback from Texas Sen. John Cornyn comes as the Senate Judiciary Committee has been planning to advance Blanche’s nomination on Thursday – but without Cornyn’s support, the vote will fail.

Cornyn said Wednesday that a planned meeting with Blanche to discuss his demands for DOJ to formally kill the fund had been canceled. The Texas Republican told CNN he still has not received the written commitment he has been demanding from Blanche and the Justice Department to formally kill the fund. As a result, he told reporters, he is not prepared to vote yes.

Asked by CNN if he would block the nomination if the hearing proceeds, Cornyn answered, “I’m not prepared to vote yes. Let me put it that way.”

With Cornyn and fellow Judiciary committee Republican Sen. Thom Tillis still unhappy that the DOJ hasn’t provided a written assurance to kill the fund, it’s unclear whether the committee will proceed with Thursday’s vote. Cornyn said the panel’s chair, Chuck Grassley, will determine around 4 p.m. ET on Wednesday whether to proceed with Thursday’s session.