The wait is almost over for what could be the last big legal threat to ObamaCare.

Court watchers are working themselves into a frenzy awaiting a decision on King v. Burwell, one of the most anticipated cases of the year.

On opinion days, dozens of reporters are packing into the court or swarming the steps outside, while nearly 10,000 people tune into SCOTUSblog for live updates. False reports attempting to predict the timing of the decision have only further fueled the hype.

Across Capitol Hill, Republicans in the House and Senate briefed their members for the first time on Wednesday, trying to calm fears about what could happen to the 6.4 million people whose health insurance subsidies are at stake in the case.

State Republican leaders are ratcheting up the pressure on Congress to overhaul the Affordable Care Act if the Supreme Court this month rules that subsidies on the federal exchange are invalid.

Republicans from 33 states have written to Congress as part of a coordinated message urging federal legislators to develop a plan that would free states from the pressure of setting up their own exchanges to salvage subsidies, according to the Foundation for Government Accountability, a conservative think tank.

Their industry already upended with the passage of the federal health care law, insurance companies are facing another upheaval if the Supreme Court rules that millions of Americans are not eligible for subsidies to help defray the cost of their coverage.

The court is expected to decide by the end of June or in early July whether it agrees with the plaintiffs in King v. Burwell that the language in the Affordable Care Act allows the government to offer subsidies only in those states that have established their own insurance marketplaces.

Today, the Congressional Budget Office (CBO) issued an analysis of the budgetary and economic effects of repealing the Affordable Care Act (ACA), the first such estimate to factor the law’s impact on the economy into the price tag for repealing it, a type of analysis also known as dynamic scoring. Though much of the report is predictable and consistent with past analyses by the CBO of the ACA, it is novel in the comprehensiveness of its scope, and offers three important lessons for observers and policymakers.

The strange, twisted journey to the Supreme Court of a case that threatens to unravel President Barack Obama’s namesake heath care legislation began five years ago in the quiet of a Greenville, S.C., law office.

It was summer 2010. The Patient Protection and Affordable Care Act had been signed into law a few months before on March 23. Tom Christina had been asked by his firm to study it and assess its implications for clients.

Jonathan Gruber, the Massachusetts Institute of Technology economist whose comments about the health-care law touched off a political furor, worked more closely than previously known with the White House and top federal officials to shape the law, previously unreleased emails show.

The emails, provided by the House Oversight Committee to The Wall Street Journal, cover messages Mr. Gruber sent from January 2009 through March 2010. Committee staffers said they worked with MIT to obtain the 20,000 pages of emails.

Speaker John Boehner (R-Ohio) is pushing back against the idea of Republicans simply continuing ObamaCare subsidies if the Supreme Court cripples the law.

At a press conference Thursday, Boehner was asked why a House GOP plan included repeal of the individual mandate, which would just be “veto-bait” for President Obama, and why Republicans would not just extend subsidies through the presidential election while looking for concessions elsewhere in exchange.

“Clearly, we’re interested in protecting those millions of Americans who could lose their subsidies. But, as I said, we are not interested in protecting a fundamentally broken law,” Boehner said.

“Protect the people, not the law,” said Sen. John Barrasso (R-Wyo.) in a brief phone interview, describing the mind-set of the GOP should the Supreme Court rule against the administration and strike down the federal Obamacare exchanges in King v. Burwell. The Supreme Court did not issue an opinion today, but within the next two weeks Congress may be presented with a dilemma: What should it do about the approximately 6.4 million people who would lose subsidies in 34 states?

The recently announced proposed rate increases for many insurers offering health insurance through the Affordable Care Act (ACA) exchanges have brought renewed attention to instability in health insurance markets and the long-term sustainability of the exchanges – apart from disruptions that would ensue if the Supreme Court rules in King v. Burwell that the ACA does not allow premium subsidies in states with federal exchanges.

Republican leaders are coalescing around a plan to extend the health law’s tax credits for as long as two years, while repealing other parts of the law, if the Supreme Court invalidates the credits.

The high court is expected to rule by the end of June on whether to restrict the 2010 law’s tax credits—used by low- and moderate-income consumers to help pay their insurance premiums—to the handful of states that opted to set up their own insurance exchanges.