Frustrated senators have questions about Obama’s Islamic State strategy. On Wednesday, they may get answers

Key senators of both parties are deeply frustrated with what they view as President Barack Obama’s confusing strategy for taking on the Islamic State and mixed messages to lawmakers about what sort of legal authority he needs from them to wage war against the radical Islamist militia.

On Wednesday, they will get their chance to grill Deputy National Security Adviser Tony Blinken on those issues when he appears before the Senate Foreign Relations Committee for what was supposed to be a combative but relatively routine confirmation hearing.

The White House always knew Blinken’s nomination to hold the No. 2 job at the State Department would be an opportunity for Republicans to criticize Obama’s foreign policy. Administration officials remain optimistic about Blinken's confirmation prospects — he has good relationships with lawmakers on both sides of the aisle, few in Washington question his qualifications for the job, and he can count on Vice President Joe Biden’s help in winning over his former Senate colleagues.

But the administration set Blinken up for a rougher test than expected this week when both Secretary of State John Kerry and Defense Secretary Chuck Hagel declined the committee’s invitation to appear at a separate hearing on Tuesday, Senate aides said.

Senators had hoped that the question-and-answer session with Kerry and Hagel would shed some light on Obama’s strategy for defeating the so-called Islamic State, and notably on what the White House wants Congress to include in an authorization for use of military force (AUMF) against the radical group.

Sen. Bob Menendez (D-N.J.), who chairs the committee, told Yahoo News on Monday that he supports passing an AUMF but that the no-shows raised questions about the administration’s goals.

“It's a little difficult when the administration doesn't produce any witnesses,” he said sharply. “So either they want an AUMF or they don't. They need to produce witnesses."

And sources in Congress complain that the only recent briefing on the administration’s strategy was a classified session last week with retired Marine Gen. John Allen, who has been the U.S. point man on the international campaign against the Islamic State.

Allen may have won over lawmakers, but the American public needs to hear directly from the administration what legal authority the president wants, congressional aides say.

“It’s hard to authorize war if you’re only having briefings behind closed doors,” one source said.

White House aides refuse to say whether Obama has shared specific legislative language for an AUMF with lawmakers. Instead, they cite ongoing “conversations” with congressional leaders and influential individual senators or representatives.

The White House has flatly refused to disclose publicly what it believes should be in a new AUMF. But informed sources told Yahoo News this week that there is what one official called a tentative “do-not-want list” from the administration.

First, the White House has indicated to lawmakers that it is not keen for the legislation to “sunset” — or expire — while Obama is still in office. Some Democrats who support giving the president an AUMF have said a sunset provision is the only way to ensure that congressional oversight of the war effort will have teeth, given lawmakers’ reluctance to cut off funding for troops in the field. “It is, by the administration’s own admission, at least a two- to three-year enterprise. They want an AUMF that reflects that,” one source said.

Second, administration officials have not asked for explicit permission to target Syrian forces. Some congressional officials had speculated that Obama’s decision to seek an AUMF after insisting for months that he didn’t want one reflected yet another turn in a dramatically shifting strategy — a move from targeting Islamic State and al-Qaida targets alone to also going after forces loyal to Syrian strongman Bashar Assad. That seems unlikely at this point.

Third, in some of their conversations, Obama aides have been vague about whether Congress should greenlight the potential use of American ground troops in combat. The president has launched airstrikes on IS forces, and recently doubled the number of U.S. ground troops in Iraq, but has thus far insisted that they do not have a combat role.

The sources all cautioned that behind-the-scenes conversations with Obama aides might not turn into concrete “asks” from the White House. And they underlined that the AUMF won’t pass before a new Congress convenes in January, when Republicans will control both chambers.

And whatever Congress puts forward, it almost surely won’t look like the White House’s dream AUMF.

That has Senate Republicans worrying that Obama (with the help of congressional Democrats) will pin any expansion of the war on them.

“They think their guy is a war ender, not a war starter. And they want this to be a ‘Republican escalation,’” said one GOP aide.

Senate Democrats, for their part, worry they’ll be left twisting in the wind, recalling how Obama pushed in 2013 for a congressional AUMF to strike Assad’s forces in Syria — then backed off military action at the last minute.

“It’s the indecision. It’s the vacillating. It’sjust not providing the clarity and the road map for senators and representatives to take up the weightiest issue they can take up,” said one senior Democratic congressional aide. “We just can’t trust them.”

There’s another wrinkle. The committee includes two potential Republican presidential contenders for 2016: Marco Rubio of Florida and Rand Paul of Kentucky. Rubio has generally taken a more hawkish line, while Paul is well known for his dislike of military intervention. Both have been sharply critical of Obama. And Democrats on the panel will surely keep the prospect of a Hillary Clinton candidacy in mind.

All of that could make for some fireworks when Blinken goes before the committee at 2:45 p.m.