Story highlights Susan Rice had been scheduled to speak to the panel Tuesday

Samantha Power served as the US ambassador to the United Nations under Obama

(CNN) The House intelligence committee has delayed classified testimony expected this week from former Obama national security adviser Susan Rice as the panel is now working to bring forward another former Obama official as soon as this month: Samantha Power.

Power, who like Rice also served as the US ambassador to the United Nations under Obama, has agreed to come before the committee, sources say. The panel is still finalizing a date, but her testimony could occur before the August recess.

Republicans have pushed to bring Power and Rice before their committee in a bid to learn whether they improperly " unmasked " -- or revealed the identities typically blacked out in intelligence reports -- of Trump associates. But Democrats have scoffed at the GOP push, a sign of the partisan strife that still exists over the direction of the committee's probe into alleged Russia's interference in the US elections.

According to sources familiar with the matter, Rice had been scheduled to speak to the panel Tuesday, but the committee has delayed her testimony for a later date. Rice, who has strongly denied any wrongdoing , declined to comment through a spokesperson, but is still expected to come before the panel at some point. Power has repeatedly called for an investigation into alleged Russian interference in the election, and has expressed a willingness to cooperate.

The delay of Rice's testimony would amount to at least the third time the panel has pushed back a scheduled witness' testimony. It also delayed hearing from Trump associate Roger Stone and former adviser J.D. Gordon. The GOP leader of the House Russia probe, Mike Conaway, said last week that the investigation is going "frustratingly slow."

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