In December, when a federal appeals court agreed to hear former President Donald J. Trump’s sweeping claims to be immune from charges of plotting overturn the 2020 election, it laid out a lightning-fast briefing schedule, asking the defense and prosecution to file their papers on successive Saturdays during the Christmas and New Year’s holidays.

A three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit also moved with unusual alacrity in setting up a hearing for arguments on the issue, scheduling the proceeding on Jan. 9, just one week after all of the papers were submitted — a remarkably short window by the standards of the judicial system.

But after sending up what appeared to be clear signals that they intended to swiftly resolve this phase of the immunity dispute — which lies at the heart of both the viability and timing of Mr. Trump’s trial on the election subversion charges — the appeals court judges have yet to issue a decision.

The implications are already coming into focus. On Friday, the Federal District Court judge overseeing election case, Tanya S. Chutkan, formally scrapped her plan to start the trial on March 4. She was bowing to the reality that time had run out to get the proceeding going by then, mostly because of the wrangling over Mr. Trump’s immunity claim, and said she would set a new date “if and when” that matter is resolved.

The disconnect between the expectations set up by the panel’s early moves to expedite the case and the weeks that have now accumulated without a ruling has captured the attention of some legal experts who are closely watching the case.

It has also caught the eye of Mr. Trump’s lawyers, who have been watching from the sidelines with something akin to quiet glee. Each day that passes without a ruling bolsters their strategy of seeking to postpone the trial until after the presidential race is decided.