Tax reform legislation will get votes in Congress in October and November, President Trump's legislative director suggested Monday.

White House legislative director Marc Short said at an event with free-market groups in downtown Washington that the timeline for tax reform anticipated having the House of Representatives mark up legislation after Labor Day. Then, the bill should hit the House floor in October and then the Senate in November in order to hit Trump's desk before the end of the year.

"Hopefully we'll have completion by mid-November," he said.

First, Congress would have to navigate a tricky legislative schedule, including passing a budget and raising the debt ceiling.

Short said Congress would be able to move tax legislation quickly, in contrast to its struggles with healthcare.

Conservative and business groups are set to rally support for tax reform, he said. "We didn't have that lead time with healthcare" to organize a coalition to back legislation, he said, but outside groups are being "galvanized" to support tax reform.

Short and Treasury Secretary Steven Mnuchin were joining an event hosted by two free-market groups affiliated with the Koch network: Americans for Prosperity and Freedom Partners.

The event was announced after White House and congressional Republicans negotiators said last week that they would drop the idea of a border-adjusted corporate tax, a policy that the Koch groups waged a major campaign to kill.

Short and Mnuchin both said tax reform had to be done this year.

"This is a pass/fail exercise, and we will pass tax reform," Mnuchin said.