Rep. Joe Sestak's allegation that the White House offered him a job to drop out of the Pennsylvania Senate primary race against Arlen Specter is a crime that could lead to the impeachment of President Obama, Rep. Darrell Issa said.

But the decision by the Pennsylvania congressman not to elaborate on a so-called deal also could become a political problem as Sestak tries for the U.S. Senate seat.

The White House reportedly is going to formally address the allegation in the next few days. In the meantime, Issa, R-Calif., is one of many inside and outside Washington who want the Democratic Senate primary candidate to explain in detail what offer the White House made...