WASHINGTON - President Donald Trump intends to nominate a Boeing executive to serve as deputy secretary of defense.

The Trump administration has struggled to fill top Pentagon positions, with two of its four previous selections having withdrawn.

A White House announcement Thursday says Trump plans to nominate Patrick M. Shanahan to be the No. 2 official at the Pentagon. If confirmed by the Senate, he would succeed Robert Work, an Obama administration holdover.

The White House also announced plans to nominate a budget chief, deputy budget chief, assistant secretary of defense for homeland defense, a deputy to the Pentagon's policy chief, and director of an office charged with providing independent analysis of military programs.