Negotiations were sputtering late Sunday on a package of nearly $500 billion in aid to small businesses and health care providers while expanding COVID-19 testing capacity, with some haggling left to be done over the measure's finer points.

Discussions were seen continuing into early Monday on a few remaining issues, such as whether the Centers for Disease Control and Prevention or National Institutes of Health should administer a new $25 billion virus testing program.

Multiple sources familiar with the talks, who weren't authorized to speak publicly, said beyond the testing provisions there were other open items and it wasn't clear how quickly a deal might come together.

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By late Sunday momentum had slowed considerably from earlier in the day. Treasury Secretary Steven Mnuchin, the administration's point man for the talks, and top Democratic leaders fanned out across the Sunday morning talk shows exuding optimism that they were on the cusp of a deal.