President Donald Trump’s tweet in advance of the crucial jobs report may have violated federal guidelines barring officials from commenting on data before its release.

Trump tweeted, at 7:21 a.m. Eastern, “Looking forward to seeing the employment numbers at 8:30 this morning.” The numbers provided reason to look forward — an 18-year low on unemployment, and 223,000 jobs created.

See:U.S. adds 223,000 new jobs as unemployment falls to 18-year low in May

The bond market did have a reaction to Trump’s tweet, as the yield on the 10-year TMUBMUSD10Y, 0.666% increased after the tweet, a move consistent with increased expectations of economic growth. The yield picked up even more after the jobs report actually came out.

The rule Trump may have violated is set out by the Office of Management and Budget, in the heretofore dry, Statistical Policy Directive No. 3.

The chairman of the Council of Economic Advisers — Kevin Hassett, currently — and the president are allowed to get briefed on the jobs report. However, “agencies must ensure that adequate steps (e.g., sequestering those granted access) are taken to prevent prerelease disclosure or use. So long as there is no risk of prerelease disclosure or use, prerelease access is permitted.”

Here’s what they are required to do: “Except for members of the staff of the agency issuing the principal economic indicator who have been designated by the agency head to provide technical explanations of the data, employees of the Executive Branch shall not comment publicly on the data until at least one hour after the official release time.”

Two areas of wiggle room seem to emerge — one, whether Trump is covered as an “employee of the executive branch,” and two, whether the tweet without numbers can be construed as a “comment.”

White House press secretary Sarah Sanders told CNBC the comment was appropriate since “he didn’t put the numbers out.”

National Economic Council Director Larry Kudlow said he was briefed by Hassett and called the president Thursday night. “I wanted him to know the numbers, by law and custom, that is correct,” Kudlow said on CNBC.

“He chose to tweet,” Kudlow added. “I don’t think he gave anything away, I think this is all according to routine.”

The OMB and the Labor Department’s inspector-general didn’t return messages. The Labor Department referred inquiries to the White House.

Jason Furman, who previously was chairman of President Obama’s Council of Economic Advisers, tweeted that the president should never see them again. Austan Goolsbee, who also held that role for Obama, pointed out how sensitive it is.

Tony Fratto, who was a spokesman for the Treasury Department under President George W. Bush, said he’s not sure Trump broke the law.

Justin Wolfers, a professor at the University of Michigan, said Trump’s tweet now sets up a dilemma for future reports.

As MarketWatch’s Rex Nutting pointed out in a column last year criticizing the president’s tweet on the jobs report at 8:45 a.m., Trump is not the first president to have crossed lines. President Dwight Eisenhower leaked the jobs report ahead of time, right before Election Day in 1954, 1956 and 1958.

Opinion:Trump’s tweet erodes trust in objectivity of government data