Senate Judiciary Chairman Lindsey Graham reversed course Tuesday, Oct. 8, and announced he'll open a Ukraine inquiry that would give President Donald Trump's personal attorney, Rudy Giuliani, an opportunity to testify in a counter to the impeachment inquiry by House Democrats.

Graham has previously said he would not open such an investigation, pushing instead for someone outside of politics at the Department of Justice to look at matters involving Ukraine, including Trump's and Giuliani's allegations about the actions of former Vice President Joe Biden and his son.

"Given the House of Representatives' behavior, it is time for the Senate to inquire about corruption and other improprieties involving Ukraine," Graham said on Twitter, citing actions leading to the firing of Ukraine's top prosecutor.

"Therefore I will offer to Mr. Giuliani the opportunity to come before the Senate Judiciary Committee to inform the committee of his concerns," Graham, a Republican and close ally of Trump, said on Twitter.

Graham's counter-attack on the House's impeachment inquiry came after days of pressure from top Trump allies including Donald Trump Jr. for Graham to act. It presents the Trump White House with a high-profile congressional forum to present its own narrative about unsubstantiated allegations about Biden, a potential challenger to Trump in 2020.

But it also would put Giuliani on the record about his months-long public and private effort to push Ukraine's government to launch a probe even as Trump himself was blocking military aid to Ukraine's new government.

A hearing with Giuliani potentially would turn the spotlight over to some of Biden's competitors in the Democratic primary who sit on the Judiciary Committee — Kamala Harris, Cory Booker and Amy Klobuchar.

In response to Graham's proposal, Harris tweeted, "Good. I have questions."

Graham accused House Democrats of conducting a one-sided investigation, but it's not clear yet how extensive his probe will be.

"We'll hear from Giuliani and then determine what, if any additional witnesses need to be called," said Graham spokeswoman Taylor Reidy.

Giuliani said on CNN that he would have to consider whether the information he has falls under attorney-client privilege, but added, "Given the nature of his invitation about my concerns I might be able to do it without discussing privileged information."

Until now, Graham had deferred to the Senate Intelligence Committee led by Republican Chairman Richard Burr and top Democrat Mark Warner, who have been quietly conducting their own probe into a whistle-blower complaint about Trump's Ukraine actions entirely behind closed doors. Graham had also told reporters he would not investigate the Bidens, saying that would effectively shut down the Senate on other matters.

Bloomberg's Jordan Fabian contributed to this report.

This article was written by Steven T. Dennis, a reporter for Bloomberg.