The Indiana senator offered a rare GOP rebuke of Trump, saying he has "a habit of losing not just his own elections, but losing elections for others."
The push to repeal the 2002 Iraq War and 1991 Gulf War authorizations for military force have steadily gained bipartisan momentum in recent years.
The 2002 law authorizing the use of military force against Iraq's Saddam Hussein could be repealed after 20 years.
Sen. Todd Young (R-Ind.) and Sen. Jeanne Shaheen (D-N.H.) crafted an alternative bill they call pragmatic. Peace groups believe it threatens confrontation with Iran.
A U.S.-backed coalition led by the Saudis is impeding the delivery of cranes for a key port in Yemen.
Dissatisfaction with the unpopular war is growing on Capitol Hill -- even among traditional supporters of the kingdom.
Sen. Todd Young (R-Ind.) hopes testimony on delayed U.S. aid and other problems will boost skepticism of the kingdom's actions.