Here's what Congress is sending to Ukraine this week: eight U.S. senators to meet with leaders of the country's interim government.

Here's what Congress isn't sending to Ukraine: an aid package for the people of the embattled nation.

Congress has been embroiled for the past few days in a battle over a proposed package, and the House passed a bill last week to provide $1 billion in loan guarantees. The Senate Foreign Relations Committee then amended that bill Wednesday, adding additional sanctions against Russians and Ukrainians who were responsible for violence as well as those who undermined Ukraine's sovereignty.

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The Senate's measure also includes asset freezes and visa revocations for certain Russian officials and creates changes at the International Monetary Fund.

And that's where the aid package hits a snag.

Republicans oppose tying any overhaul that would expand the IMF's lending capacity to the bill.

"The IMF money has nothing to do with Ukraine," House Speaker John Boehner, R-Ohio, said Thursday.

(Senate Republicans also want to change a new IRS rule that would curb the political activities of nonprofit groups, an unrelated issue).

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Senate Democrats have cried foul. Senate Majority Leader Harry Reid, D-Nev., even went so far as to blame the Koch brothers, billionaires who back conservative causes, for stalling the package.

And one prominent Republican is lashing out at his colleagues who are holding up the aid package: Sen. John McCain, R-Ariz.

"Where are our priorities? Is the IMF, whether it's fixed or not fixed, more important than the lives of thousands of people?" McCain said on the Senate floor Thursday evening.

"You can call yourself Republicans. That's fine, because that's your voter registration. Don't call yourself Reagan Republicans," McCain said. "Ronald Reagan would never, would never let this kind of aggression go un-responded to by the American people."

McCain is among the eight lawmakers heading to Ukraine this weekend. He is set to be joined by several Senate colleagues: Richard Durbin, Democrat of Illinois; John Barrasso, Republican of Wyoming; John Hoeven, Republican of North Dakota, Ron Johnson, Republican of Wisconsin; Christopher Murphy, Democrat of Connecticut; Jeff Flake, Republican of Arizona; and Sheldon Whitehouse, Democrat of Rhode Island.

The Senate now heads into a week-long recess with an aid package undone. The Senate does not return to Washington until March 24.