Of course, the explanation for the sudden interest is the press reports that President Trump asked then-FBI Director Comey to drop the investigation of former national security adviser Flynn.
Putting aside politics, and whether that actually happened and sticking to the law, obstruction of justice is a federal offense that covers any attempt by someone to "influence, obstruct, or impede" -- including "corruptly" -- the "proper administration of the law" in a pending proceeding, including by Congress.
The main obstruction statutes are 18 USC 1503 (Influencing or injuring officer or juror generally), 1505 (Obstruction of proceedings before departments, agencies, and committees) and 1512 (Tampering with a witness, victim, or an informant).
The most likely statute that would apply if the President did what the press is saying he did, is 18 USC 1505, which states, in part:
Whoever corruptly, or by threats or force, or by any threatening letter or communication influences, obstructs, or impedes or endeavors to influence, obstruct, or impede the due and proper administration of the law under which any pending proceeding is being had before any department or agency of the United States, or the due and proper exercise of the power of inquiry under which any inquiry or investigation is being had by either House, or any committee of either House or any joint committee of the Congress—
Shall be fined under this title, imprisoned not more than 5 years or, if the offense involves international or domestic terrorism (as defined in section 2331), imprisoned not more than 8 years, or both.Which leads to the question of whether it is an impeachable offense. I will leave that discussion for another day but would remind readers that the impeachment of President Nixon had, at its core, obstruction of justice, charging the President with a variety of acts, including
4) Interfering or endeavoring to interfere with the conduct of investigations by the Department of Justice of the United States, the Federal Bureau of Investigation, the office of Watergate Special Prosecution Force and congressional committees.Before I get a bunch of hate mail, I am not comparing the allegations against the President, which have not been proven, to Watergate. I am just answering questions and pointing out the serious nature of the allegations.
Related stories:
What Is Obstruction of Justice? An Often Murky Crime, Explained
Trump may have committed obstruction of justice — here’s what that is