If at first you don’t succeed, try, try again. And then, if you are a lobbyist working on the renewable energy tax credits, try a few more times.

The Solar Energy Industries Association (SEIA) counts eight Senate votes so far this year on bills that would extend breaks to the solar and wind energy industries. The tax breaks enjoy widespread support in Congress, and the industries say they are critical to their growth.

Senate Republicans, backed by business lobbies like the U.S. Chamber of Commerce, object to “pay-fors” in bills that would offset the costs of the tax breaks to the treasury.

This week, there could be a ninth vote, to shut off debate on an extender bill.

The new bill, released by Senate Finance Committee Chairman Max Baucus (D-Mont.) requires insurance companies to include mental health coverage that’s on par with other medical benefits they offer; plugs a multibillion-dollar hole in the Highway Trust Fund that pays for highway construction and mass transit systems; and provides disaster-relief money to flooded communities in the Midwest.

All of this is meant to sweeten the pot for wavering Republicans and some of their backers downtown.

The bill also extends solar investment tax credits worth an estimated $1.8 billion for eight years, and provides nearly another $1 billion to encourage residents to install solar panels on their homes.

Thousands of jobs and billions invested in the solar industry are at risk if Congress doesn’t extend the tax breaks, the industry contends.

“It’s a very good bill, but we need it now,” said Monique Hanis, a spokeswoman for SEIA.

“Projects and manufacturing plans are already being putting on hold,” she wrote in an e-mail.

SEIA’s chairman, Roger Efird, the CEO of Suntech North America, is in Washington this week to lobby lawmakers to support the tax credit extension. He has a personal story to tell: Suntech has put off plans to build a facility in the United States until Congress approves the extension.