WASHINGTON — An emergency aid package for the beleaguered Ukrainian government has become entangled in a partisan dispute over the International Monetary Fund, with House Republicans resisting President Obama’s personal pleas to extend the reach of a Ukraine rescue plan by including long-sought changes to the fund’s structure.

The administration already has pledged $1 billion in United States loan guarantees to the government in Kiev, and the House responded quickly, approving an aid package on Thursday with overwhelming support from both parties. But House Republicans rebuffed the president on a request to include language that would extend a separate billion-dollar package of loans from the fund to $1.6 billion by expanding loan limits for countries like Ukraine.

A draft aid plan pending before the Senate Foreign Relations Committee does include the language. If it remains, House, Senate and White House negotiators will square off this week, as the government in Kiev teeters on the brink of a default. Adding to that tension, Congress intends to be on recess the following week.

“There’s been a lot of talk in Congress about these issues,” Mr. Obama said on Thursday. “Once again, I’m calling on Congress to follow up on these words with action, specifically to support the I.M.F.’s capacity to lend resources to Ukraine and to provide American assistance for the Ukrainian government so that they can weather this storm.”