Sen. Mitt Romney (R-Utah) is expected to support a subpoena for records related to the work of former Vice President Joe Biden's son Hunter for Ukrainian energy firm Burisma, CNN reports.

Why it matters: Romney's plans emerged just one day after he expressed concern that the investigation "appears" politically motivated, aimed at hurting Joe Biden's presidential run. But a spokesperson for Romney said on Friday the senator changed his mind after Senate Homeland Security Committee Chairman Ron Johnson (R-Wis.) assured him the probe will be handled behind closed doors.

Where it stands: Romney split with the GOP last month when he voted to convict President Trump in the Senate impeachment trial. However, Republicans already had enough votes to secure Trump's acquittal.

In this case, his likely vote in favor of a subpoena could be critical for Republicans, who have an 8-6 majority on the committee. If he were the sole Republican defector, the motion would fail in a 7-7 tie.

The big picture: Johnson's investigation comes as Senate Finance Chair Chuck Grassley (R-Iowa) has also embarked on an effort to obtain documents related to the Bidens and Burisma.

What they're saying: “Sen. Romney has expressed his concerns to Chairman Johnson, who has confirmed that any interview of the witness would occur in a closed setting without a hearing or public spectacle," Romney's spokeswoman Liz Johnson said. "He will therefore vote to let the chairman proceed to obtain the documents that have been offered.”

What to watch: The Senate Homeland Security Committee is scheduled to vote next Wednesday on the subpoena related to the panel's probe of conflict-of-interest allegations against the Bidens.