Negotiators are hoping to seal a deal by Monday.
House conservatives are also expected to force a vote on impeaching the IRS commissioner.
Lawmakers face a government funding deadline at the end of the month.
Lawmakers are likely to leave for the long recess without a compromise on Zika funding.
Congress has little time left to address Zika funding before the recess.
The Senate will take up a House-passed Zika deal the White House has vowed to veto.
Both chambers will consider spending bills before leaving for recess.
The mass shooting will likely change the defense authorization.
Lawmakers may also consider Puerto Rico aid and spending bills.
The House will start debate on an appropriations bill.