WASHINGTON (Reuters) - With long-term transportation legislation still eluding lawmakers, House Republican leaders are planning another temporary extension of federal highway and transit funding that would keep construction projects and gas tax collections on track.

Transportation Committee Chairman John Mica said on Tuesday that he expects a "clean," or non-controversial bill to emerge in coming days that the chamber can pass before the extension authorizing current funding, approved last September, expires on March 31.

The Senate, which has already passed a transportation bill, would have to agree for any extension to take effect.

The previous multi-year U.S. transportation law expired in September 2009. Since then, programs that fund road, bridge and transit projects and gas tax collections have been kept alive by a series of temporary extensions.

Gas tax receipts that flow into a trust fund are the main source of revenue for those construction programs.

Another stop-gap is in the works because a five-year, $260 billion transportation proposal has gone nowhere in the House of Representatives this year due to its size and controversial transit financing and energy provisions pushed by Republicans.

Mica said details of a new extension were still under discussion, including the expected time frame. Other congressional sources said the proposal was likely to run up to 60 days, but nothing had been decided.

Mica would not be pinned down on discussing the length of the proposal, but said the House wants to ensure temporary funding and no shutdowns of construction projects.

Many lawmakers consider a long-term transportation plan an important election-year priority considering billions of dollars in capital works spending and the millions of job associated with highway and transit construction.

The Senate last week approved a $109 billion measure, which keeps funding at current levels for two years.

Senate Majority leader Harry Reid and Public Works Committee Chairman Barbara Boxer both urged the House on Tuesday to quickly adopt the Senate bill instead of pushing forward with another extension.

But the House has no plans at the moment to formally consider its own long-term measure. Also, adopting the Senate bill as written would be viewed as a setback for Speaker John Boehner, who has invested political capital in transportation as a way to create jobs in a tough economy.

(Reporting By John Crawley; Editing by Eric Walsh)