Vice President Mike Pence has delayed his trip to the Middle East next week so he can stay in Washington for a crucial vote on tax reform, the fate of which may come down to his tie-breaking vote in the Senate.

"Yesterday the White House informed Senate Leadership that due to the historic nature of the vote in the Senate on tax cuts for millions of Americans, the VP would stay to preside over the vote," Pence spokeswoman Alyssa Farah said in a statement.

Pence is expected to depart for Egypt and Israel on Wednesday, one day after Senate Republicans plan a final vote on their tax bill, which has undergone several changes in the conference committee process.

"He looks forward to having constructive conversations with both [Israeli] Prime Minister Netanyahu and [Egyptian] President el-Sisi to reaffirm President Trump's commitment to our partners in the region and to its future," Farah said of Pence.

House and Senate Republicans reached an agreement Wednesday morning on a final tax bill that will lower individual rates and drop the corporate tax rate to 21 percent. The legislation preserves a number of existing tax breaks, while doubling the standard deduction and expanding the child tax credit. Conferees also decided to partially retain state and local tax deductions that Republicans from high-tax states had opposed eliminating altogether.

To get the bill to President Trump's desk by Christmas, the Senate will need to vote on it next week. Republican leaders can only lose two votes from their conference to ensure the bill's passage, and Sen. Bob Corker, R-Tennessee, has already signaled he plans to vote against the legislation. If two votes were lost, the bill would have 50 "yes" votes from the GOP, and Pence could vote to break the tie.

In exchange for voting in favor of the Senate tax bill earlier this month, Maine Sen. Susan Collins demanded a vote on legislation that would mitigate the impact of repealing Obamacare's individual mandate. Collins told reporters on Wednesday that she is undecided on the final bill.