Speaking to Fox News’ Sean Hannity on Monday, Graham, a Republican, said he would be willing to be Biden’s “best ally” in the Senate with regards to drawing up a list of how the U.S. would react if China does “bail out” the “war criminal” Russian President Vladimir Putin.

Graham was speaking after several news outlets had reported that U.S. officials told them Moscow had asked China for financial assistance and military support following Russia’s invasion of Ukraine. Both Beijing and Moscow have denied the reports

Graham urged the Biden administration not to “make the same mistake” with Beijing as it did with Moscow and demonstrate immediately how it would impose sanctions on China.

Several Republicans had criticized Biden for not threatening to impose stricter sanctions against Russia sooner, and only announcing plans to do so just days before the invasion.

Sen. Ben Sasse (R-NE), a member of the Senate Select Committee on Intelligence, described Biden’s earlier sanctions—following the recognition by Putin of breakaway Ukrainian regions as independent—as “too little, too late” in a February 22 statement. The invasion occurred on February 24.

“If you believe the Chinese are going to help Putin survive by providing military equipment, economic assistance […] put on the table, for China to read, the sanctions that will come your way if you help Putin,” Graham said on Monday.

“I will help you as a Republican, Mr. President, President Biden, if you will write down sanctions, secondary sanctions against China, what will happen to the Chinese economy if they bail out this war criminal Putin. I will be your best ally in the United States Senate.

“Write it down now so China can read it, because nobody believes you unless you write it down,” Graham added.

The reports came as White House national security adviser Jake Sullivan flew out to Rome, Italy, on Monday to speak to his Chinese counterpart, Yang Jiechi, about Russia’s war with Ukraine.

According to The Guardian, a U.S. official expressed concerns that China “already decided” that it was going to give financial and military support to Russia, and that they “underscored” their intent during the talks.

“The question really is whether they will go further,” the unnamed official added.

Liu Pengyu, spokesman for the Chinese Embassy in the U.S., previously said that he had “never heard” of the claims that Moscow had asked Beijing for military equipment and economic assistance. The Chinese Foreign Ministry accused the U.S. of “spreading disinformation” with the claims.

Kremlin spokesman Dmitry Peskov also denied reports Russia had asked China for military assistance in relation to attacks in Ukraine.

“Russia possesses its own independent potential to continue the operation. As we said, it is going according to plan and will be completed on time and in full,” he said.

The White House has been contacted for comment.