Graham said he will block a vote by the Senate Armed Services Committee on Austin's nomination to become the new Central Command chief, until the four-star general provides the panel his insights into the White House's postwar plan for Afghanistan.
Panel member Sen. Kelly AyotteKelly AyotteBottom Line How Gorsuch's confirmation shapes the next Supreme Court battle THE MEMO: Trump set to notch needed win with Gorsuch MORE (R-N.H.) backed Graham's efforts to postpone the committee's confirmation of Austin's nomination.
Austin is slated to replace outgoing Central Command chief Marine Corps Gen. James Mattis.
With the block, it is unlikely the four-star general's nomination will reach the Senate floor for a vote until after the upcoming congressional recess next week.
On Tuesday, President Obama announced that he would be withdrawing half of the 68,000 U.S. troops remaining in Afghanistan by the end of this year.
"Tonight, I can announce that over the next year, another 34,000 American troops will come home from Afghanistan. This drawdown will continue. And by the end of , our war in Afghanistan will be over," Obama told a joint session of Congress during Tuesday's State of the Union speech.
That plan falls in line with the administration's recent decision to accelerate the handover of all security operations to the Afghans by this spring.
Those efforts coincide with postwar recommendations made by Marine Corps Gen. John Allen, former top U.S. officer in Afghanistan, before he stepped down from command this year.
But as the presumptive head of Central Command, Graham asked Austin to discuss the coming troop drawdown, as well as other yet-to-be disclosed aspects of the American drawdown strategy in Afghanistan "and see if they make sense to you."
During the hearing, Graham pointed out the conflict between Austin and the White House over postwar troop levels during the U.S. drawdown in Iraq.
Austin, who was the top American officer at the time of the Iraq withdrawal, suggested the Pentagon leave behind a 16,000-man force in Iraq after the U.S. withdrawal from the country in December 2011.
The Obama administration, on the other hand, suggested a maximum of 10,000 U.S. boots on the ground in Iraq is all that would be needed to maintain security in the country and back up Iraqi security forces in the country.
In the end, the White House opted not to leave any troops in the country, due to a lack of a troop immunity deal with Baghdad.
But Graham said he did not want the same political calculations that created the disconnect between the administration and the Pentagon in Iraq to be repeated in Afghanistan.
"You need to call Gen. Allen," Graham added.
Graham has already launched attempts to block confirmation on former Nebraska Republican Sen. Chuck HagelChuck HagelLobbying World The US just attacked Syria. So where's Congress? Senators tear into Marines on nude photo scandal MORE and White House counterterrorism chief John Brennan, the administration picks to head up the Pentagon and CIA respectively.
Senate Republicans are planning to filibuster the Hagel nomination during a scheduled cloture vote set for Friday. Senate intelligence panel chief Sen. Dianne FeinsteinDianne FeinsteinDemocrats exploring lawsuit against Trump Overnight Finance: Dems explore lawsuit against Trump | Full-court press for Trump tax plan | Clock ticks down to spending deadline Comey to testify before Senate Judiciary Committee MORE (D-Calif.) announced her committee would postpone voting the Brennan bid out of committee until after next week's recess.