The two lawmakers have been embroiled in the controversy since last year.
Check it out:

Two members of the House Ways and Means Committee tangled Sunday over allegations in the Internal Revenue Service’s (IRS) political targeting scandal.

Rep. Charles Boustany (R-La.) slammed the Obama administration for what he called “obstruction” of a Republican investigation into the extra scrutiny given to conservative groups that applied for tax-exempt status.

Rep. Sander Levin (Mich.), the top Democrat on Ways and Means, said Republicans have been unable to uncover any evidence that the White House was involved with the effort, despite a year of trying.