WASHINGTON (Reuters) -The U.S. Senate planned an initial vote on a stopgap spending measure on Tuesday to keep federal agencies running past the end of this week, while Congress continues to negotiate bills to fund the government through the next fiscal year.

President Joe Biden's Democrats, who control both chambers of Congress, are expected to avoid an embarrassing partial government shutdown just six weeks before the Nov. 8 midterm elections, when control of Congress will be at stake.

The bill, which would extend overall government funding through Dec. 16, was facing resistance because of an energy permitting reform measure.

If the Senate blocks consideration of this two-pronged bill, Majority Leader Chuck Schumer and House of Representatives Speaker Nancy Pelosi were expected to promptly retool the measure to ensure quick passage of the spending components and keep the government fully operating.

The spending provisions include $12.3 billion in new money to help Ukraine turn back Russia's invasion, House of Representatives Appropriations Committee Chairwoman Rosa DeLauro said in a statement.

This includes military and economic assistance. In addition, it authorizes Biden to direct the drawdown of up to $3.7 billion for the transfer to Ukraine of excess weapons from U.S. stocks.

In early September, Biden requested $11.7 billion in military and economic aid.

Amid reports of Russian forces threatening the safety of Ukraine's nuclear power plants and Russian President Vladimir Putin hinting he might use nuclear weapons against Ukraine, the legislation would appropriate $35 million "to prepare for and respond to potential nuclear and radiological incidents in Ukraine," according to a bill summary.

Congress has resorted to this kind of last-minute temporary spending bill in 43 out of the past 46 years due to its failure to approve full-year appropriations in time for the Oct. 1 start of a federal fiscal year, according to a government study.