Barack Obama will unveil a national climate change plan on Tuesday, offering the first real glimpse of how he intends to make good on one of the most stirring promises of his inaugural address.

In a video posted on the White House web site on Saturday, the US president reiterated his view that climate change was the challenge of a generation.

The goals he will outline in his speech at Georgetown University will be equally ambitious, encompassing "a national plan to reduce carbon pollution, prepare our country for the impacts of climate change, and lead global efforts to fight it", Obama said.

There will likely be strong reactions from Republicans in Congress, who oppose action on climate change as well as from fellow Democrats. Some campaigners will also doubtless argue Obama should do much more to stop global warming.

In concrete terms, there is widespread expectation Obama will announce he is using his executive powers as president to direct federal government agencies to reduce the greenhouse gas emissions that cause climate change, and to encourage energy efficiency.

He is also expected to step up government programmes promoting the expansion of renewable energy sources such as wind and solar power especially on public land.

The video also seemed to suggest that Obama would seek to involve his council of scientific advisors in drawing up a strategy for protecting American cities and coastlines from the worst consequences of climate change.

Some of the policy elements in Obama's address were previewed earlier in the week in a speech by the White House climate advisor, Heather Zichal.

In a forum sponsored by the New Republic magazine, Zichal suggested Obama would direct the Environmental Protection Agency to begin regulating greenhouse gas emissions from coal-fired power plants.

Coal-fired power plants are the single largest source of America's greenhouse gas emissions – responsible for up to 40% of carbon pollution – and have long been a target of campaigners.

The Obama administration has already taken steps to raising standards on new power plants. But it has balked until now at imposing tougher standards on existing power plants – a measure which would deliver the biggest cuts in greenhouse gas emissions.

There was intense speculation ahead of Tuesday's speech about whether Obama would promise to curb emissions of existing facilities.

The president's comments in a speech in Berlin this week seemed to suggest he was prepared for bolder action.

"Our dangerous carbon emissions have come down, but we know we have to do more, and we will do more," Obama told the crowd.

Zichal in her remarks this week also indicated EPA regulations would be part of Obama's climate plan.

"Going forward, obviously the EPA is going to be working very hard on rules that focus specifically on greenhouse gas emissions from the coal sector," she said. "They're doing a lot of important work on that space."

Tuesday's speech is likely to provoke strong reactions across the political spectrum.

John Boehner, the house speaker, pre-empted the speech by several days, telling Fox news on Thursday it would be "absolutely crazy" to use the EPA to reduce carbon emissions.

On the opposite end of the political divide, Obama will be under intense pressure on Tuesday to offer some assurances to opponents of the Keystone XL pipeline.

The project, intended to carry tar sands crude from Alberta to refineries on the Texas Gulf Coast, has become a key issue for campaigners, who say it is a core test of Obama's environmental commitments.

A number of prominent Democrats – as well as 145 veterans of Obama's election campaigns – have come out against the pipeline.