WASHINGTON — The U.S. presidential campaign has focused heavily on jobs, pushing other once high-profile issues to the side. It dismays activists who have spent decades promoting environmental issues, gay rights, gun control and other topics to the center of national attention.

Topics suffering downgrades in campaign attention include these:

CLIMATE CHANGE

Of the roughly 50,000 words spoken in this month’s three presidential debates, for example, none were “climate change,” ”global warming” or “greenhouse gas.”

With fewer than half of Americans believing that human activity contributes to global warming, according to Pew Research, President Barack Obama talks far less about climate change than he did four years ago. When he locked up the Democratic nomination in June 2008, he said future generations would recall “this was the moment when the rise of the oceans began to slow and our planet began to heal.”

Obama hasn’t come close to making such claims in recent months. Last June, 3,100 U.S. temperature records were broken and much of the nation was in drought, said Daniel Kessler, spokesman for 350 Action Fund, which tries to raise awareness of global warming. And yet the three presidential debates produced “absolute silence on climate science,” Kessler said.

GUNS

Gun rights sometimes have played big roles in U.S. elections. In 1993, the recently elected President Bill Clinton signed the Brady Bill, which required background checks on many gun buyers. A new ban on assault weapons soon followed. But it contributed to heavy Democratic congressional losses in 1994, and the law expired 10 years later.

Despite high-profile mass shootings — including those involving Rep. Gabrielle Giffords in early 2011 and dozens of Colorado movie theater patrons in July — questions about gun rights and gun control have generated little discussion this year.

A voter asked about assault weapons in the second presidential debate on Oct. 16. Obama cautiously spoke of “seeing if we can get an assault weapons ban reintroduced.” Republican challenger Mitt Romney said he favors no new gun laws.

IMMIGRATION

In recent years, immigration has been a big issue in national elections. George W. Bush backed a pathway to legal status for many illegal immigrants when he ran for president in 2000. But Republican activists and members of Congress increasingly took hard stands against illegal immigrants.

In this year’s Republican primaries, Romney said illegal immigrants should be encouraged to “self-deport.” He has softened his rhetoric somewhat since then. He told Hispanic leaders in June he would replace Obama’s executive order allowing 800,000 young illegal immigrants to remain in the country with a long-term solution. But Romney didn’t detail his plans, and immigration has played a smaller role in the general election than it did in the primary.

GAY RIGHTS

Questions of same-sex marriage and other gay rights issues were not mentioned in the debates.

That’s not to say the nominees haven’t taken stands. Early in his term, Obama helped clear the way for gays and lesbians to serve openly in the military. This year he embraced same-sex marriage, which Romney opposes.

The gay-oriented group Log Cabin Republicans gave Romney a tepid endorsement this week. “If LGBT (lesbian, gay, bisexual, transgender) issues are a voter’s highest or only priority, then Governor Romney may not be that voter’s choice,” the Log Cabin Republicans endorsement said. The group said it believed Romney would do a better job of cutting spending and creating jobs.

Those issues have dominated the campaign. Both campaigns have warned of the looming “fiscal cliff” — the package of huge tax hikes and spending cuts scheduled to hit Jan. 1 — but no one has come close to offering a viable solution.

Meanwhile, advocates for improving schools, fighting poverty, fighting crime and other issues — which have played big roles in past elections — have struggled to get a word in edgewise this year.