Trump said he will not be signing something like the Omnibus bill again. It expires Sept. 30.

Democrats and Republicans would be in the middle of a shutdown while campaigning

"The bill includes full Appropriations legislation and funding for the remaining 11 annual Appropriations bills through the end of the fiscal year, September 30, 2017. "

https:// appropriations.house.gov/news/documentsingle.aspx?DocumentID=394859