Gov. Jerry Brown made a final push Wednesday to secure legislative support for a tax increase that would fund road construction and become a major piece of his legacy.

Facing mounting opposition from environmentalists and anti-tax groups, the Democratic governor joined a rally of construction workers on the Capitol steps imploring undecided lawmakers to get on board.

Brown and top Democratic lawmakers are working against a self-imposed deadline to approve the $5 billion a year increase in taxes and fees by Thursday.

The governor visited a closed-door meeting of Assembly Democrats Wednesday trying to round up the votes he'll need to reach the two-thirds supermajority required to increase taxes. His pleas capped a week of cajoling and prodding lawmakers with rallies in the districts of undecided legislators.