U.S. Secretary of Education Betsy DeVos took over the Education department, first and foremost, to move the ball forward on school choice, her long-time passion. She’s been in the job less than six months, but already, time may be running out to get a sweeping school choice initiative over the finish line, at least this year.

One big reason: There have been broad, school choice proposals floated, but no details.

The Trump administration has been signaling for months that it may push for a federal tax credit scholarship program, allowing individuals and companies to get a break on their taxes if they donate to a scholarship-granting organization. That could help low-income or special needs students cover private school. But it’s July, and there aren’t specifics on that. (Sources say that there could be details soon, however.)

President Donald Trump’s budget includes some new initiatives aimed at ramping up school choice, including $250 million for a private school voucher demonstration program, and allowing $1 billion in Title I money to follow students to the public school of their choice. But, again, there are ton of questions—both big picture and nitty-gritty—about how those proposals would work

Maybe more importantly, Republicans in Congress don’t seem terribly excited about the school choice proposals in the budget, which come at the expense of long-standing education programs. And lawmakers—and maybe even the Trump administration—don’t seem poised to include the tax credit scholarships as part of a broader overhaul of the tax code, the most likely vehicle. (More on that below).

If a major new school choice program doesn’t gain traction in either a tax rewrite, or the budget bill, it may not happen this year.

“They’re losing their window to get this done,” said John Bailey, who worked on education in the White House during President George W. Bush’s tenure. “We don’t have all the details we need.”

So what do we still need to know about DeVos’ school choice initiatives? And what’s their political prognosis? Here’s a rundown.

What are the specifics on the private school choice program?

We know the Trump administration wants to allocate $250 million to states and/or school districts for private school choice. And we know this will be voluntary. But there are a bunch of other questions: How big would these grants be? How many states or districts would get them?

Some states, like choice-friendly Arizona, are all but counting on the money, said Mike Griffith, a school finance analyst who works with the Education Commission of the States. But, despite DeVos’ assurances that the program won’t be mandated, other states are worried that the feds are going to “force something on them,” Griffith said.

The power of the grants, too, will depend on their size and how many states or districts end up receiving them. “If 10 states qualify and you take that $250 million and it ends up being, like five bucks per kid,” then it’s not going to be much of a game-changer, Griffith said.

The Trump administration wants to place the program in the Education Innovation and Research program. That opens up a whole different can of worms, as my colleague Sarah Sparks wrote here.

How would the Title I portability program work?

The Trump administration’s budget called for making about $1 billion portable, meaning the money could follow students to the public school of their choice. It seems the Trump administration is eyeing a pilot program in the Every Student Succeeds Act that allows districts to try out a weighted student funding formula. In fact, the administration put a notice in the Federal Register last month, asking for comment on how the pilot should work—a sign that the department wants to get going on it.

Districts that participate in the pilot can combine federal, state, and local dollars into a single funding stream tied to individual students. English-language learners, kids in poverty, and students in special education—all of whom cost more to educate—would carry with them more money than other students. Some districts, including Denver, are already using this type of formula with state and local dollars.

But changing the way that Title I dollars flow would likely require congressional approval, said Max Eden, a senior fellow at the Manhattan Institute, a conservative think tank. That’s far from a sure thing.

What’s more, Title I doesn’t function like a straight-up scholarship. Schools within the same state might get different amounts of money per kid due to factors like concentrations of poverty, Griffith said.

“It starts to get very confusing with Title I, though, because the formula is based on density,” he said.

The Trump administration will need to sort out what happens, for example, when a Title I-eligible student decides to take their federal money to a non-Title I school, potentially bringing with them new requirements.

Whatever happened to the federal tax credit scholarship program?

Trump gave a shout-out to Denisha Merriweather, who benefitted from Florida’s tax credit scholarship program, in his first speech to Congress. He also dropped by the Sunshine State to visit a school that benefits from the initiative. That had everyone expecting a big tax credit scholarship proposal, possibly based on legislation introduced by Sen. Marco Rubio, R-Fla., and Rep. Todd Rokita, R-Ind., in short order. But we haven’t seen any concrete proposals from the administration on this front yet, although that could change soon.

But getting a proposal over the finish line is another story. It seems that lawmakers aren’t wild about the idea of attaching the federal tax-credit scholarship program to a broader tax-reform package. That means there may not be a legislative vehicle for the program. And White House officials have indicated that the tax credit scholarship is something they would be willing to compromise away, one source said.

“It’s unlikely to move as part of a tax reform plan, which to me says it’s unlikely to move at all,” Eden said.

Will Congress go for any of this?

We know this much: It’s not a slam dunk.

Republicans may control Congress. But they aren’t exactly jumping for joy over the school choice proposals in Trump’s budget request, especially because they are paid for in part by cuts to popular programs, like after-school funding.

In fact, Sen. Roy Blunt, R-Mo., the chairman of the panel that oversees K-12 spending, told DeVos in a recent hearing that her budget request was “difficult to defend.” And even Trump administration allies, like Sen. James Lankford, R-Okla., pressed DeVos on how a Title I public school choice initiative was different than the Obama administration’s approach of using competitive grants to drive its agenda.