Congress returns to Washington today after another week-long recess and is expected to spend part of their first week back debating a U.S. aid package to Ukraine.

A man removes a Ukrainian flag after seizure of a base in Crimea. (Max Vetrov/AP)

With U.S. officials warning that Russia may be on the verge of expanding its territorial conquest deeper into eastern Ukraine, and with President Obama spending part of the week at meetings with European leaders, now would seem like a good time for lawmakers to make a bold statement to the world by reaching an agreement on how far the United States is willing to go to help the new Ukrainian government.

But nothing moves quickly or simply through Capitol Hill these days, and while almost everyone agrees that the United States needs to provide money and other aid to Ukraine, the details of an aid package appear to be the newest flashpoint in the partisan battles between the House and Senate.

So where do things stand?

The Senate is expected to hold a procedural vote Monday evening on a bipartisan aid package that would provide $1 billion in loan guarantees for Ukraine and target Russian and Ukrainian officials involved in starting the standoff. The agreement would authorize $50 million for democracy, governance and civil society assistance and $100 million in security assistance for Ukraine and other countries in the region.

But the deal also includes changes long-sought by the White House that would shift about $63 billion in International Monetary Fund money from a crisis fund to a general account. Doing so would make good on a 2010 pledge by the Obama administration and ensure greater U.S. influence over the world body.

Senate Foreign Relations Committee Chairman Robert Menendez (D-N.J.) said in a speech over the weekend at a meeting with European officials in Brussels that any sanctions imposed on Russia by the U.S. and European allies have to be "strong and significant enough to force [Russian President Vladimir Putin] and the small group of elites that surround him to re-calculate and change Russia’s course of action."

But at least five Republican senators are opposed to including changes to the IMF in the aid deal. Sens. Ted Cruz (R-Tex.), Mike Enzi (R-Wyo.), Mike Lee (R-Utah), Rand Paul (R-Ky.) and Pat Roberts (R-Kan.) co-signed a letter Friday signaling their opposition to the IMF language, describing those provisions as "antithetical to the driving purpose of the underlying legislation." The senators said they are concerned that U.S. contributions to the IMF would double "yet actually undermine our influence in that body in a manner that provides no actual relief to Ukraine."

The GOP opposition, however, isn't expected to stop the aid package from clearing the procedural hurdle Monday night and passing the Senate later this week.

But then there's the House.

Republicans have already steered an aid package through the chamber that includes the $1 billion in loan guarantees and a separate measure condemning Russia's takeover of Crimea. But Speaker John A. Boehner (R-Ohio) has said that there's no need to include the changes to the IMF in the final deal -- meaning he will have to decide whether to strip out the IMF-related language in the Senate measure and send it back for final approval, or gauge potential support to include it and get the aid package passed quickly.

With developments moving quickly in Ukraine, the House Foreign Affairs Committee is already working on another bill that would codify in law the executive orders Obama has signed that sanction about a dozen senior Russian and Ukrainian officials and pave the way for more sanctions on a broad swath of the Russian economy. The new measure calls on Obama to impose additional sanctions on Russian officials with influence over the country's foreign policy, instruct the White House to provide updates to Congress on Russian officials involved in political activity, and require the Treasury Department to more closely monitor the activity of Russian banks.

The measure is designed in part to address calls from lawmakers of both parties to more aggressively target top Russian officials and other elements of the Russian economy.

Sen. Kelly Ayotte (R-N.H.), who was part of a congressional delegation that visited Ukraine over the weekend, said Sunday that the United States should be working on imposing further penalties, because “The Russian economy is a one-trick pony. They’re totally focused on natural gas and oil. And so if we were to impose greater sanctions on economic sectors, I think we could have a significant impact on Putin, and then he would get the message.”

And House Intelligence Committee Chairman Mike Rogers (R-Mich.) said Sunday that he hopes Congress is willing to provide sufficient military assistance to the Ukrainian government. He told NBC's "Meet the Press" that the assistance would be in lieu of U.S. military action in the region. The military assistance could include "small arms so they can protect themselves. Maybe medical supplies, radio equipment, things that they can use to protect themselves, defensive-posture weapon systems."

Bottom line: Even if Congress approves an aid package this week -- and that's still a big unknown -- it's clear that lawmakers are nowhere near done debating what to do about the situation in Ukraine.