House Republicans cast pro-environmental votes just 5 percent of the time in 2016, while their Democratic colleagues tallied a 94 percent voting record, according to the League of Conservation Voters. That makes the 114th Congress the most politically polarized in the 46-year history of LCV's Scorecard, the new numbers released Thursday show.

In the Senate, the average GOP member was voting pro-environment 14 percent of the time, while the Democrats' average was 96 percent. The gap of 85 points between the Republican and Democratic average scores in 2016 was only slightly smaller than the record 87-point divide in 2015. As a whole, Congress was more divided than ever in the two years before the most recent election.

Many "pro-environment" votes in 2016 were to stop GOP efforts to roll back protections, noted Sen. Tom Carper (D-Del.), ranking member of the Senate Environment Committee. Carper's LCV score was 94 percent.

"We're at a point now where we'll be judged by our success in the bad things we keep keep from getting done," he said. Although he saw some opportunities for bipartisanship on environmental issues—most notably on President Trump's stated goal of infrastructure investment—he anticipated more partisan fights ahead. "For a while, we'll be battling it out."

The gulf between the parties on Capitol Hill also coincides with a trend in support lawmakers receive on the campaign trail: In the 2016 election cycle, 88 percent of the $31.3 million that the fossil fuel industry donated in Congressional races went to Republicans; 12 percent to Democrats, according to data compiled by the Center for Responsive Politics. In comparison, as recently as 2008, political contributions from the oil, gas, and coal industries favored the GOP over the Democrats by a 75-25 percent split. In 1990, the Republicans' edge was 56-44 percent.

Robert Brulle, a sociologist at Drexel University, said as Congress has become more politically polarized on climate change in particular, so has the American public. "Congressional votes indicate to the committed party members the party stance on environmental issues. These elite cues then drive public concern," he said. "Overall, the latest LCV scores paint the picture of a highly polarized Congress, and in turn, lead to continuation of the polarization in U.S. public opinion."

LCV's 2016 scorecard was based on 38 votes on environmental issues in the House, which is the largest number of votes since the environmental group began its annual tally of Congressional voting records in 1970. It reflected a slew of measures introduced both to block the Obama administration's climate change initiatives and to roll back long-standing protections under the Clean Water Act, Clean Air Act, Endangered Species Act and other laws. "Under Speaker Paul Ryan, the U.S. House remains the most anti-environmental in history," the LCV said in its report. The votes "left virtually no issue unscathed and included attacks on many of our cornerstone environmental laws."

Only 17 votes on environmental issues were scored in the Senate, reflecting the fact that many of the measures considered in the House never came to a vote there. In the Senate, filibuster rules mean that 60 votes are needed to pass most legislation and the leadership often won't spend floor time on measures that can't garner enough bipartisan support.

But in one case last year, Congress succeeded in using special rules to vote against one Obama administration regulation with a simple majority vote: the "Waters of the U.S." rule, designed to protect streams and tributaries. President Obama vetoed that measure, but the rule is now being challenged in the courts and is among those being targeted for elimination by the Trump administration.

The White House, in fact, plans to revisit many of the issues that Congress considered in 2016. "If you want to know which protections for your health and environment are at risk in the Trump era, look no further than the 2016 Scorecard," said Alex Taurel, LCV's deputy legislative director. "This is the playbook corporate polluters will try to enact into law in the coming years."

The House GOP first descended into single digits on the scorecard in 2013 and has scored 5 percent or less ever since. In all, 119 House members, all of them Republicans, scored a zero, signifying an unalloyed anti-environmental voting record, in 2016. That's 27 percent of the House. Among those scoring zero were three key committee chairmen: Rep. Lamar Smith (R-Texas) of the Science committee, Rep. Rob Bishop (R-Utah), of Natural Resources, and Rep. Mike Conaway (R-Texas), of Agriculture.

In the Senate, 16 members, all Republicans, scored a zero, including the new Attorney General Jeff Sessions (R-Ala.), and former presidential candidate Ted Cruz (R-Texas.)

The highest scorer by far among Senate Republicans was Sen. Susan Collins (R-Maine) with 76 percent. The second-highest scoring Republican in the Senate, with 46 percent, Sen. Kelly Ayotte of New Hampshire, lost her Senate seat in 2016.

Collins, who was the sole Republican last week to vote against President Trump's pick to run the Environmental Protection Agency, Scott Pruitt, is one of the few Republicans recently to win an LCV endorsement, in her 2014 reelection race. The LCV aims to be a non-partisan organization and to provide an objective look at Congressional voting records on environmental issues, but due to increasing partisanship on the issue, the group has been able to find few Republicans to endorse in recent years. It endorsed Hillary Clinton during the Democratic primaries in 2016, marking its earliest endorsement ever.

Thirty-three Senate Democrats and 83 House Democrats had perfect 100 percent pro-environmental voting records, including both the former and current minority leaders Sen. Harry Reid (D-Nev.) and Sen. Charles Schumer (D-N.Y.), and House Minority Leader Nancy Pelosi (D-Calif.) The LCV did not score House Majority Leader Ryan (R-Wisc.) because he votes at his discretion.