(Bebeto Matthews/AP Photo)

NEW YORK-In an address to an environmental group that fiercely opposes the Keystone XL pipeline Monday evening, Hillary Clinton made no mention of the project.

At a fundraising dinner for the League of Conservation Voters, Clinton spent most of her speech expressing support for the president's environmental policies, the need to stay vigilant in combating climate change and the risks around natural gas drilling, but she ignored the pipeline. The group has worked to kill its construction.

The possible 2016 presidential candidate praised the "unprecedented action" President Obama has taken on climate change saying it "must be protected at all costs."

"The science of climate change is unforgiving, no matter what the deniers may say, sea levels are rising, ice caps are melting, storms, droughts and wildfires are wreaking havoc," Clinton said. "The political challenges are also unforgiving, there is no getting around the fact the kind of ambitious response required to effectively combat climate change is going to be a tough sell at home and around the world at a time when so many countries including our own are grappling with slow growth and stretched budgets."

Clinton said technological advancements are likely the key to solving climate change urging the crowd to "dare greatly and lead boldly" in order to "protect our heritage and preserve our future."

"If we act decisively now we can still head off the most catastrophic consequences," Clinton said. After her speech, Clinton sat with environmental activists including Democratic donor and Keystone opponent Tom Steyer.

The decision to ignore Keystone was especially interesting because earlier Monday evening she appeared at a New York City fundraiser for Democratic Sen. Mary Landrieu who is in a tough run-off in Louisiana . Landrieu strongly supports construction of the Keystone XL pipeline, on the other end of the environmental issue spectrum to the League of Conservation Voters.

Clinton has not weighed in on whether she supports Keystone, dodging questions on the issue previously, despite pressure from both Republicans to state her position as well as the progressive wing of the Democratic Party to not only weigh in, but to oppose the pipeline. Clinton has said since she oversaw the permitting process for the project it would be inappropriate for her to state her position.

Gene Karpinski, president of the League of Conservation Voters spoke before Clinton and mentioned Keystone calling it "dirty and dangerous," but speaking to reporters after the event he said "it's not critical at this moment" for Clinton to express support for their side of the issue.

"She's already made it clear this is a decision the president should make in consultation with the secretary of state and she's not going to offer her opinion," Karpinski said. "I wouldn't have expected anything different than that."

When asked if it would be a deal breaker in supporting a candidate in 2016, Karpinski pointed to 2014 candidates they supported that also backed Keystone including Alaska Sen. Mark Begich and North Carolina Sen. Kay Hagan, who both lost in November.

Landrieu is in a re-election battle that has gone to a run-off against GOP Rep. Bill Cassidy, also a proponent of the Keystone XL pipeline and a critic of the president's environmental policies. The run-off is this Saturday and Landrieu has been trailing in the polls. The Monday evening fundraiser was held at the New York City home of longtime Democratic donors and Clinton supporters Sarah and Victor Rozner. Tickets started at $1,000, but the next two tiers were $2,600 and $12,600, according to an invitation obtained by ABC News.

Clinton also headlined a New Orleans rally for Landrieu just before Election Day in early November. Landrieu not only supports Keystone, but she tried to save her seat pushing a bill through the Senate approving the pipeline, but the legislation failed by one vote earlier this month. The League of Conservation Voters openly opposed the legislation.

The pipeline would carry tar sand oil from Canada to the United States Gulf Coast, making it a key issue in Louisiana. It's also an important issue in Canada and Clinton has dodged questions on the pipeline at different events in the country. She will travel there again next month speaking in Winnipeg.