Trump wanted to veto bill to keep government open
Behind-the-scenes: When the spending bill had been negotiated and finalized, White House chief of staff Reince Priebus phoned the former House Speaker John Boehner and told him the president doesn't like how the negotiation came out and is thinking about vetoing the bill. Boehner has told associates that Priebus asked him if he could talk Trump into signing the spending bill. Boehner said he would.
Ten minutes later, Boehner's phone rang. It was the President. Boehner made a couple different arguments to Trump about why he should sign the spending bill:
He told Trump he should be happy about the fact that he doesn't have to give a dollar of domestic spending in exchange for increases in military spending. And he got a substantial boost in military spending.
The most important argument Boehner made: the last thing you need right now is a government shutdown.
https://www.axios.com/trump-wanted-to-veto-bill-to-keep-government-open-2416977147.html