Tennessee Sen. Bob Corker, the top Republican on the Senate Foreign Relations Committee, cited the issue involving 501(c)4 groups as one of the outstanding issues left on the Ukraine bill. He signaled that adding the provision could be a way to get the GOP on board with the legislation, especially because it includes changes to the International Monetary Fund opposed by some congressional Republicans.

“I know for Republicans, especially in the House, to even be willing to deal with the IMF issue, I know it’s very important, and for many Republicans in the Senate,” Corker said Tuesday of the 501(c)4 issues.

( PHOTOS: Ukraine turmoil)

On First Amendment grounds, Congressional Republicans have generally opposed the proposed rule, written by the Internal Revenue Service and the Treasury Department, cracking down on political nonprofits and have pressed the administration for a delay.

But despite the last-minute complications, the influential panel is poised to take up the Ukraine package on Wednesday at 2:30 p.m. As of late Tuesday, a final agreement had not been reached and legislative language had not been publicly unveiled.

The committee’s chairman, Sen. Bob Menendez (D-N.J.) sketched out the key provisions of the Ukraine package in a Washington Post op-ed published Tuesday night. Among the highlights are loan guarantees for Ukraine, as well as $50 million for “democracy, governance and civil society assistance” and an additional $100 million for “enhanced security” for Ukraine and surrounding nations.

The legislation also levels sanctions against Russian officials complicit in “significant corruption” in Ukraine, and it would also allow for more sanctions against both Russians and Ukrainians responsible for undermining the small Eastern European nation’s sovereignty.

“Russian actions at home and abroad must be viewed in a broader context, not as isolated incidents but as connected events in a troubling pattern of behavior that cannot continue unchecked,” Menendez wrote in the Post. “Ukrainian sovereignty cannot be violated for looking westward and embracing ideals rooted in freedom.”

The panel wants to quickly move through the bill this week. It’s less clear whether the full Senate will be able to clear it: Senate Majority Leader Harry Reid (D-Nev.) said “of course” senators could pass the package before next week’s congressional recess, “unless there’s some holdup by the Republicans.”

The IMF had been one of the biggest sticking points in the congressional response to Russia’s recent invasion of Ukraine, which has prompted unusual bipartisan cooperation on Capitol Hill. But the Obama administration has frustrated congressional Republicans by pushing for the IMF changes.

Revisions agreed to by the IMF board in 2010 would reconfigure the amount of money that the United States and other countries contribute to the organization. But that change can’t be implemented without congressional approval and Republicans have raised concerns that taxpayer dollars could be at risk.

“I’d like to see the IMF piece included also,” Corker said Tuesday afternoon. “There are some issues right now relative to that and if we cannot get the IMF issues worked out, I’d like to go ahead with the rest of the package. But one of the issues is actually paying for it.”

The Republican-controlled House easily passed legislation last week to provide financial assistance to Ukraine but that legislation didn’t include the IMF provision. Some House Democrats said at the time that while they support the IMF changes, that debate shouldn’t slow down assistance to Ukraine.

In his op-ed, Menendez defended including the IMF reforms in the Ukraine package, saying they would “allow Washington to leverage significant support from the IMF for Ukraine today and for similar crises in the future.”

The demand involving the proposed rule for political nonprofits also complicates the debate. And news that those demands were getting tangled up in the negotiations over an assistance package to Ukraine drew immediate rebuke from Hill Democrats.

“It’s terribly wrong,” said Michigan Rep. Sander Levin, the top Democrat on the House Ways and Means Committee, of tying the two issues together.

The Senate developments came as top Obama administration officials headed to Capitol Hill on Tuesday to brief lawmakers on the latest developments in the crisis in Ukraine.

The administration officials included Victoria Nuland, the assistant secretary of state for European and Eurasian affairs; Derek Chollet, the assistant secretary of defense for international security affairs; Robert Cardillo, the deputy director for intelligence integration, David Cohen, the undersecretary for terrorism and financial intelligence at the Treasury Department; and Daleep Singh, the deputy assistant secretary for Europe and Eurasia at Treasury.

The classified briefing came as the House prepared to vote on a resolution that condemns the violation of Ukraine’s sovereignty, while calling for sanctions against Russian officials and other agencies responsible for the invasion into the Crimean region of Ukraine. The resolution passed the House easily on a 402-7 vote, with one member voting present.

Rep. Ed Royce (R-Calif.) and Rep. Eliot Engel (D-N.Y.), the top lawmakers on the House Foreign Affairs Committee, are still working on a package of sanctions that would “bolster democracy in Ukraine and counter Russia’s intervention,” a committee spokesman said Tuesday.

Meanwhile, the Senate unanimously passed a resolution Tuesday evening written by Sens. Dick Durbin (D-Ill.) and Dan Coats (R-Ind.) that condemned Russia’s incursion into Ukraine, suggested targeted sanctions on Russian leaders and urged suspension of Russia’s membership in the G8. The resolution also calls on FIFA to reconsider Russia’s hosting of the World Cup in 2018.

Manu Raju and Burgess Everett contributed to this report.