WASHINGTON (CNN) -

Tom Steyer, the billionaire environmentalist who's pledged to spend millions in this year's midterm contests, will discuss climate change with top White House officials and Treasury Secretary Jack Lew this week, according to officials.

At the Wednesday meeting, Steyer will also sit down with former Treasury Secretary Hank Paulsen and former Housing and Urban Development Secretary Henry Cisneros to confer on a forthcoming report assessing the economic effects of climate change.

The Steyer-funded outside advocacy group, NextGen Climate, pledged in May to spend $100 million in midterm election races to go after so-called "science deniers" who reject claims humans are responsible for global warming and climate change.

Steyer has set himself up as the chief adversary to the Koch brothers, the billionaire industrialists who fund a web of conservative groups. He's a fierce opponent of the Keystone XL oil pipeline, which is still under consideration by the Obama administration.

Last week President Barack Obama went after Republicans who deny man made climate change, saying they posed a "serious threat" the country's future and comparing their claims to suggesting the moon is made of cheese.

The White House embarked upon a major environment effort starting in early June, when Obama unveiled proposed new restrictions on coal plants. This week other members of his administration will discuss the effects of climate change that scientists say are already being seen, including extreme weather.

The President himself will address the issue Wednesday at the League of Conservation Voters' annual dinner in Washington.