Sens. Elizabeth Warren (D-MA), Gary Peters (D-MI) and Mike Lee (R-UT) are holding the nomination of former Pentagon acquisition chief Frank Kendall to become Air Force secretary, according to sources close to the matter. Warren's office declined to comment, while Peters' and Lee's offices did not immediately respond to requests for comment. Sources said Warren is holding Kendall's nomination in a bid to extract additional ethics and recusal pledges from him, while Peters is unhappy with a recent Air Force...