President Obama is expected to name former Sen. Chuck Hagel (R-Neb.) as his next Defense secretary early next week, according to reports.

White House officials would not confirm that Hagel has been selected by the president, but multiple reports cited outside sources saying that the announcement could come on Monday or Tuesday.

Hagel’s selection, which was first reported by Foreign Policy on Friday, would set off a major confirmation battle.

Pro-Israel groups have mobilized against Hagel since his name was leaked as the leading contender last month, and several Republican senators have come out in opposition.