Nearly a dozen Republican members of Congress will break ranks with leaders of their party on Thursday, and call for action against climate change.

The mini-rebellion a week before the pope visits Congress appears timed to ratchet up the pressure on Republican presidential candidates and congressional leaders to soften a party line of casting doubt – or simply denying – the existence of climate change.

So far, at least 10 House Republicans have signed on to the resolution acknowledging that human activity contributes to climate change, and calling for actions to respond to the threat of climate change.

The res­ol­u­tion was drafted by Chris Gibson, a former US army colonel and congressman from New York who is not seeking re-election.

The resolution, calling for “conservative environment stewardship” was endorsed by representatives Ileana Ros-Le­htin­en and Car­los Cur­belo of Flor­ida, Robert Dold of Illinois, Dave Reich­ert of Wash­ing­ton, Pat Mee­han, Ry­an Cos­tello, and Mike Fitzpatrick of Pennsylvania, and Richard Hanna and Elise Stefanik of New York, according to the National Journal.

A number of those representatives are also not seeking re-election or are from moderate districts.

Campaigners who have been working for months to break Republicans’ blanket climate denial said they were hoping for more converts.

Catholic climate activists said on Wednesday they were planning to deliver copies of the pope’s encyclical on climate change – a sweeping denunciation of environmental degradation and global inequality – to each of the 166 Republican members of Congress.

Church leaders were also pushing Congress to support Barack Obama’s climate change plan and fund climate aid for developing countries.

“It gives us a more dynamic entry to treat the issue,” Oscar Cantu, the bishop of Las Cruces, told a news conference in Washington.

It is unclear how the Republican leadership will respond. The party has vowed to defeat Barack Obama’s plan to cut carbon pollution from power plants, the pillar of his plan to fight climate change.

The House speaker, John Boehner, has sidestepped the issue of climate change, saying: “I am not a scientist.” A number of Republican presidential candidates including Senator Ted Cruz of Texas deny the existence of climate change. Others, such as former senator Rick Santorum and former governor Jeb Bush have called on the pope to steer clear of the issue – although Bush later softened his language.

Democrats and campaigners had been quietly cultivating moderate house Republicans for months to try to neutralise the highly partisan profile of energy and climate change issues.

The pope, and his framing of climate change as a moral issue – rather than an economic or scientific concern – provided the perfect opportunity, according to Alan Lowenthal, a Democratic member of the House from California and a leader of the Safe Climate Caucus.

“Behind the scenes there are Republicans who understand they cannot be in denial and we are being supportive of them,” he said in an interview last June around the time of the pope’s pastoral letter on climate change. “They care what the future is. They just find it difficult to be out there all alone, and maybe this will give them the courage to move forward.”

By any standards outside of those of Republicans in Congress – where a majority denies the human contribution to climate change, or opposes action on climate change – the resolution would be seen as exceedingly timid.

It calls on the house to “study and address the causes and effects of measured changes to our global and regional climates”.

The formulation is bound to outrage some because there is no doubt that climate change is caused by rising concentrations of carbon dioxide and other greenhouse gases in the atmosphere.

The resolution also limits the potential scope of any action, saying efforts to deal with climate change should not impose any costs on the economy.

But after five years in which Republicans have blocked all efforts to deal with climate change, it’s a start.