The new picks to lead the Pentagon and US Treasury face key hurdles Tuesday in the Senate, as President Barack Obama fleshes out his second-term cabinet amid trying times for defense and finance.

If they are confirmed as expected, as soon as this week, Secretary of Defense pick Chuck Hagel and Treasury nominee Jack Lew will be greeted with a series of crises, including $85 billion in automatic spending cuts set to kick in on Friday unless Congress acts with lightning speed.

Democrats, who control the Senate, are confident Hagel, a Republican former senator and Vietnam War veteran who endured a bruising confirmation hearing, will get the 60 votes necessary Tuesday to bring his confirmation to the floor for a vote.

His nomination had been delayed by Republicans angered by Hagel's positions on Iran, nuclear weapons and Israel, and who had sought more information on his finances and his speeches to international groups since his Senate retirement.

An earlier attempt to overcome that barrier fell one vote short, but in the intervening week Republican Senator John McCain has said Hagel deserved an "up or down" floor vote.

Another Republican in the Senate, Richard Shelby, has also said he will now support Hagel.

For Lew, Obama's chief of staff who was tapped last month to succeed Timothy Geithner at the Treasury, was actively involved in the 2011 budget negotiations that led to the creation of the sequester set to take effect on Friday.

Democrats including Senate Finance Committee chairman Max Baucus have suggested Lew was expected to be confirmed, and Shelby said he would support Lew's nomination.

Iowa Republican Chuck Grassley, however, has sought more disclosure from Lew about the compensation he received in the early 2000s as executive vice president of New York University.

Baucus has scheduled a committee vote for Tuesday, and with Geithner having stepped down from the Treasury, Senate Majority Leader Harry Reid said Monday he wants to bring a full vote to the floor "before the end of this week."

If Republicans move to block Lew, as they did with Hagel, Democrats would again need to assemble a "supermajority" of 60 out of 100 senators to push the appointment through.

Lew and Hagel would join Obama's cabinet at a fragile time with the looming sequester, which could lead to the loss of hundreds of thousands of jobs amid already sluggish economic growth, and reduced military readiness.

Obama has a handful of other posts to fill, including replacements for secretaries of transportation, energy, labor and interior.

Hagel has been the most controversial nominee to be considered by the Senate for Obama's second term. But the president also faces tough going for John Brennan, his pick to head the Central Intelligence Agency.

On Sunday, McCain threatened to block Brennan's confirmation over the lack of White House information on the attack on a US outpost in Benghazi, Libya last September 11 that killed four Americans including the US ambassador.