Flake would not say outright that the White House misstepped by delaying strikes to secure congressional approval, but he noted "it seems a bit of a strange way to go about it."
His comments put Flake in step with fellow Arizona Sen. John McCainJohn Sidney McCainTrump attacks Meghan McCain and her family In Montana, a knock-down redistricting fight over a single line McCain: Ivanka Trump, Jared Kushner had 'no goddamn business' attending father's funeral MORE (R) who has advocated U.S. military intervention in Syria since the early days of the civil war there.
On Sunday, President Obama announced the White House would delay proposed military strikes against the Syrian government in order to seek congressional authorization for the operation.
Obama stated he was prepared to conduct strikes in Syria, without U.S. lawmakers' blessing, in retaliation for Assad's use of chemical weapons.
But seeking official authorization from Congress could unify the country behind any effort to strike the Syrian government, the president noted.
That said, Flake said he had serious concerns over why the administration opted to hold off on military action in Syria.
"I think all of us recognize that it is a bit of a strange situation when you come to Congress to [seek] authorization for action you can already take," Flake told reporters on Capitol Hill Tuesday.
"There are a lot of questions as to why we waited" to take action in the country, he said.
The biggest concern, according to Flake, is efforts Assad's forces are reportedly taking in anticipation of an American attack.
Obama has stated the delay to seek authorization from Congress will not affect U.S. plans.
Planned U.S. operations against Syria "will be effective tomorrow, or next week, or one month from now, and I am prepared to give that order," the president said.
Flake openly questioned that assertion, saying the fluidity of the Syrian civil war could nullify the White House's battle plans.
"It would seem strange that you would have the same targets available a couple of weeks later," Flake said.
Assad is reportedly moving prisoners taken by his forces to military sites across the country that could be targeted by U.S. missiles.
Syrian troops have already abandoned positions in the capital of Damascus, retreating to underground bunkers and military compounds north of the city.
But Flake was quick to point out that his support for early action in Syria was not an endorsement of full-scale U.S. operations in the country.
The Obama administration has said "again, again and again that this is not Iraq, this is not Afghanistan, this is not even Libya," he said.
The White House has expressed openness to rewriting draft language authorizing the use of force in Syria to win votes.
Secretary of Defense Chuck HagelCharles (Chuck) Timothy HagelInterpreter who helped rescue Biden in 2008 escapes Afghanistan Overnight Defense & National Security — Pentagon chiefs to Congress: Don't default Pentagon chiefs say debt default could risk national security MORE, Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey and Secretary of State John KerryJohn KerryQueen Elizabeth resting 'for a few days' after hospital stay Twenty-four countries say global net-zero goal will fuel inequality Queen Elizabeth recognizes Kerry from video message: 'I saw you on the telly' MORE came to Capitol Hill on Tuesday to lay out the administration's war plans.
House Speaker John BoehnerJohn Andrew BoehnerRift widens between business groups and House GOP Juan Williams: Pelosi shows her power Debt ceiling games endanger US fiscal credibility — again MORE (R-Ohio) and Minority Leader Nancy Pelosi (D-Calif.) have said they will back military action in Syria when the authorization vote comes to the House floor.