Lawmakers and the White House searched for ways to finance around $1 trillion infrastructure proposals without raising the gas tax or placing costs on electric vehicles, debating how much new profit the Internal Revenue Service could generate with increased enforcement efforts.The infrastructure proposal, which includes $579 billion in spending above expected federal levels and would total $973 billion over five years, has won the backing of 11 Republican senators and 10 members of the Senate Democratic caucus. A group of 10 of the lawmakers met frequently on Tuesday with top White House officials as the group aimed to put together a plan for public release, with talks set to continue.The group has discussed financing the package through a variety of public-private partnerships, regenerating existing federal funds, and increasing enforcement at the IRS to collect taxes that are owed but not paid. A draft version also included indexing the gas tax to inflation and charging an annual cost on electric vehicles as other ways to pay for the spending, which would total $1.2 trillion if extended over eight years.However, the White House has opposed increasing the gas tax, which was last raised in 1993, and charging costs on electrical vehicles, instead proposing that the plan collect additional revenue from enhanced tax enforcement. Internal Revenue Service Commissioner Charles Rettig recently has calculated that as much as $1 trillion in owed taxes may go uncollected each year, and recent negotiations among the lawmakers have focused on how much of the tax gap could be closed with new investments in the IRS.