While Americans and Congress are rallying behind President Obama’s campaign to eradicate ISIS, a senior House Democratic leader said on Monday that lawmakers must shed their “rose-colored glasses” and take a hard look at the fiscal implications of an almost-certain long-term military engagement in Iraq and Syria.

House Democratic Whip Steny Hoyer (D-MD) urged the Armed Services and Appropriations Committees to schedule hearings as soon as possible to provide taxpayers with a realistic assessment of what it may cost in the coming decade to battle ISIS -- and gauge the likely impact on the deficit and other spending priorities.

Related: Boehner Says Defeating ISIS Means Using Ground Troops

Noting that the administration of Republican President George W. Bush vastly underestimated the cost of invading Iraq and Afghanistan in the wake of the 9/11 attacks against the U.S., Hoyer said during a speech at the National Press Club, “I think any hearings . . . need to contemplate cost and we need to let the American people know that there is consequence in cost to us undertaking these responsibilities, as there was in World War II or Korea or Vietnam.”

“I think we have to look at that honestly,” he added. “Unlike in Iraq, where the administration projected less than a hundred billion in cost and it was over a trillion dollars in cost.”

The issue of cost – and how the government will finance the military endeavor – has received short-shrift as Obama forges a U.S.-led coalition of more than 40 Middle Eastern and European allies pledged to fulfill the president’s goal of “degrading and ultimately destroying” the Muslim jihadist terrorists.

The United States is spending roughly $7 million to $10 million a day on its new air war against ISIS in northern Iraq and parts of Syria – a drop in the bucket when contrasted with the hundreds of millions of dollars it spent daily fighting in Afghanistan in 2013, according to USA Today.

Related: The New Price Tag for the U.S. War Against ISIS

Adding to the tab: war planes that can cost at least $10,000 per hour to fly, Tomahawk land-attack cruise missiles launched by the Navy that go for $1.1 million apiece, and “smart” bombs that are guided to their targets by satellites that cost about $40,000 each.

Rear Adm. John Kirby, the Pentagon press secretary, told reporters last Thursday that the projected annual cost of $2.5 billion to $3.65 billion to conduct the new air strikes against ISIS hardly compares to the $77.7 billion spent during fiscal 2013 for Operation Enduring Freedom, most of which went for fighting in Afghanistan.

But just as the Bush administration low-balled the cost of its decade-long, dual missions in Afghanistan in combating al-Qaeda terrorists, some experts believe Obama’s latest venture could prove to be far more expensive than the administration is acknowledging.

Gordon Adams, a prominent military analyst at American University, recently told The Fiscal Times that the mission to stop ISIS will cost $15 billion to $20 billion a year, based on his “back of the envelope” calculations. Adams broke down those growing cost of the ISIS fight as follows: $8 billion for airstrikes in Iraq and Syria; $3 billion for training and equipment for Iraqi ground forces; $1 billion for support for moderate Syrians set to be trained in Saudi Arabia; and the rest related to building the coalition.

Related: Why We Won’t Have Enough Money to Fight ISIS

That $15 billion to $20 billion estimate from Adams would come on top of the administration’s defense budget for fiscal 2015, which begins on Wednesday, including $496 billion for personnel and general DOD operating costs as well as $58 billion for “Overseas Contingency Operations,” which covers the actual cost of wars.

The OCO, as it is known, has paid for the protracted U.S. military engagement in the Middle East with borrowing that adds to the long-term U.S. debt.

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