Republican senator: 'Jack Lew must never be secretary of Treasury'

A key Republican has vowed to block the expected promotion of White House Chief of Staff Jacob "Jack" Lew, saying he "must never be secretary of Treasury."

Lew is expected to be nominated for the treasury secretary job by the end of the week. 

A strongly worded statement by Sen. Jeff Sessions, R-Ala. -- prepared in anticipation of that nomination and obtained by Fox News -- signals the bumpy ride Lew could face during the Senate confirmation process. Sessions, the top Republican on the Senate Budget Committee, says Lew misled Congress about the White House's budget proposals and argues that should disqualify him from being put in charge of the government's finances.

"Lew, as the president's budget director, appeared before Congress and continued to insist that President Obama's budget-which Lew had crafted-would not add to the debt of the United States," Sessions said in the statement, calling Lew's comments "the most direct and important false assertion during my entire time in Washington."

Obama is expected to announce Lew's nomination later this week. 

A veteran of the Clinton White House who has held several positions in the Obama administration, Lew has previously been confirmed by the Senate. But Sessions insists this time should be different.

"At this time of unprecedented slow growth, high unemployment, and huge deficits, we need a secretary of Treasury that the American people, the Congress and the world will know is up to the task of getting America on the path to prosperity; not the path to decline," he said in the statement. "Jack Lew is not that man."

A spokesman for Sessions said the senator does not believe the Lew nomination will be successful.