(NBC NEWS) -- Moving quickly to reassure the nation that he's on top of the IRS crisis, President Obama on Thursday named budget aide Danny Wefrel as the new IRS Acting Commissioner.
The move came just hours after the president denied he knew conservative groups were being targeted by the tax agency.
President Obama also vowed the IRS will no longer target political groups.
"It is just simply unacceptable for there to be even a hint of partisanship," he said.
The president insisted he did not know that IRS agents were demanding Tea Party donor lists,
even though his top appointee in Washington was aware.
Acting IRS Commissioner Steven Miller was forced out on Wednesday.
"I promise you this, the minute I found out about it my main focus was making sure we get the thing fixed," the president said.
Still, Tea Party Republicans vow to look deeper.
"You see an administration - and a federal government under this administration - that's willing to use its power to muscle, to hardball people who don't agree with them," claimed Florida Senator Marco Rubio.