"I am reserving judgment on what will come out of the House until we see more about the substance of the proposal and the process by which the proposal will proceed," Senator Chuck Schumer said as the Senate opened.

"Hopefully, we will get details of the speaker's proposal later today. Again, time is of the essence," Schumer said.

More than two months after the Senate approved a $95 billion package of security assistance for Ukraine, Israel and Taiwan and other U.S. partners in the Indo-Pacific, House Speaker Mike Johnson said on Monday that the Republican-led House would consider the aid this week, but would do so as separate pieces of legislation.

However, to become law, the measures would have to pass the House and Senate and be signed into law by Democratic President Joe Biden. The House has already tried to pass bills providing aid only for Israel, but they were not taken up in the Senate.

The text of the bills was not released - it is expected later on Tuesday - but there would be separate measures providing assistance to Ukraine as it fights a Russian invasion, Israel after the Oct. 7 attack by Hamas and a weekend air assault by Iran, and partners in the Indo-Pacific as they face an increasingly aggressive China.

Johnson told Fox News on Tuesday that the fourth bill would include additional sanctions on Russia and Iran as well as the "REPO Act," a provision regarding the seizure of Russian assets to help Ukraine.

Biden has been pushing Johnson to allow a vote on supplemental funding, as have Senate Republicans and Democrats. But Johnson had given a variety of reasons to delay, including the need to focus taxpayer dollars on domestic issues.

Many hard-right Republicans, especially those closely allied with former President Donald Trump, who is challenging Biden in the November presidential election, have been skeptical about assisting Kyiv in its fight against Russia and fiercely oppose sending billions more dollars to Ukraine.

(Reporting by Patricia Zengerle; editing by Jonathan Oatis)

By Patricia Zengerle