A new report that the Obama administration eavesdropped on conversations between congressmen and American Jewish citizens and Israeli officials has evoked concerns that the White House abused its power for political gain.

These concerns are similar to those that led Congress to launch investigations into evidence of dirty tricks by the Nixon administration, and into the Iran-Contra affair during the Reagan years.

Congressional investigations are crucial for shining spotlights on troubling conduct, and for preventing it from recurring.

The Wall Street Journal first reported that the administration spied on meetings and telephone calls involving members of Congress and American citizens, apparently not for any real national security purpose, but to bolster its effort to win passage of the Iranian nuclear deal.

Based on interviews with numerous U.S. officials, the Journal said that the White House OK’d National Security Agency spying that encompassed not only Israeli officials, but congressmen and members of U.S. Jewish groups. This surveillance took place at a time when the administration was concerned that domestic opposition would cause Congress to reject the Iran deal.

It appears to have been used largely to help the White House win a domestic political battle, not for national security.

That raises serious questions, among them: What was the national security justification for spying on members of Congress and U.S. citizens? Who ordered it, who received the surveillance reports, and who continues to have access to them? What guidelines, if any, did the NSA use?

According to the White House, the NSA was permitted to decide for itself what to do with the information it obtained. Assuming that’s true, should the NSA be allowed to do whatever it wishes with information obtained by spying on members of Congress and private citizens?

It is not spying on foreign governments that raises the most profound questions, but rather the apparently unfettered spying on the legislative branch and U.S. citizens.

Both political parties now should press for a congressional probe — an investigation needs to be genuinely bipartisan. That will be a challenge, especially in an election year.

But the price of not finding out the truth is high. What’s at stake here is the public’s confidence in the White House, and in knowing that it has not seriously overstepped proper boundaries.