President Obama’s attorney general said Wednesday he thinks special counsel Robert Mueller legally could prosecute President Trump for obstruction of justice.

“Is there a technical case there now?” Holder said to Politico. “I think so. Now.”

But Holder said Mueller will need to make sure he has a strong case to go after a sitting president. Some Trump allies and legal experts have argued that presidents cannot be charged with obstruction.

“If you're a prosecutor, you make sure that you are building the best case. Not a technical case, but the best case, you know, that you can,” Holder explained. “You know, the [James] Comey firing. The outreaches to [Director of National Intelligence Dan] Coats and the other intel guys.”

“There are a variety of things that I can think of, technically [that could be used against Trump],” he continued. “Now, who knows what else they've got.”

Mueller appears to be building an obstruction case against Trump as he investigates Russia’s meddling in the 2016 election. Trump has denied any wrong doing, calling the Russia investigation a “witch hunt.”