Legislative Republicans are trying to rally Connecticut drivers to urge Democratic lawmakers and Governor Dannel P. Malloy to stop a looming increase in gas and diesel taxes. Republican lawmakers held a petition drive Monday in an effort to put pressure on the Democrats, the Legislature’s majority party. The petroleum gross receipts tax is a percentage of the wholesale price of gasoline and is charged to companies distributing petroleum products in Connecticut. It is scheduled to increase on July 1, from 7 percent to 8.1 percent. That tax is in addition to the state’s regular 25-cents-per-gallon gas tax and the 18.4-cents-per-gallon federal gas tax. Meanwhile, the diesel tax is scheduled to increase 3.5 cents per gallon. Democrats criticized GOP members for originally backing the tax increase in 2005.