WASHINGTON (Reuters) -U.S. House of Representatives Speaker Mike Johnson said on Wednesday he plans to hold a vote on a standalone Israel aid bill despite a Congressional Budget Office report showing it could increase the federal deficit.

In the first major legislative action under Johnson, House Republicans unveiled their bill on Monday seeking to provide $14.3 billion for Israel by cutting Internal Revenue Service (IRS) funding.

The House could vote on the bill and pass it with Republican support as soon as Thursday. But it is unlikely to become law, as it faces stiff opposition in the Democratic-controlled Senate and the White House has threatened a veto.

Democrats and some Republicans oppose the plan, choosing instead to support Democratic President Joe Biden's request for a $106-billion bill including funding for Ukraine's war effort, increased border security, humanitarian aid and efforts to push back against China in the Indo-Pacific, as well as money for Israel.

Johnson voted against aid to Ukraine before he became speaker, but Republican Senator Josh Hawley said he told a group of senators at a lunch meeting on Wednesday that he does support some money for the Kyiv government, just not combined with Israel aid.

Johnson's office did not immediately respond to a request to verify his remarks.

But Johnson told Fox News in an interview on Wednesday that Ukraine's funding would be linked with border security.

"Those two things are going to be handled together," Johnson said.

The non-partisan Congressional Budget Office (CBO) said on Wednesday that the IRS cuts and the Israel aid in the standalone bill would add nearly $30 billion to the U.S. budget deficit, currently estimated at $1.7 trillion.

Johnson rejected that assessment, telling reporters: "We don't put much credence in what the CBO says."

To become law, any legislation must pass the House, the Senate and be signed into law by Biden.

Democrats accused Johnson's Republicans of wasting time by backing a partisan measure rather than a bill that would pass quickly to address the crisis following the Oct. 7 attack on Israel by Iran-backed Hamas militants from the Gaza Strip.

The top Senate Democrat, Chuck Schumer, said on Tuesday the bill would be dead on arrival in the upper chamber.

The Biden administration said Biden would veto such a bill if it reached his desk, calling it "bad for Israel, for the Middle East region, and for our own national security."