WASHINGTON — The Senate plans crucial votes Saturday on two of the year's most incendiary political issues: repealing the military's "don't ask, don't tell" policy on gays and lesbians and revamping immigration laws to help put children of illegal immigrants on a path to citizenship.

Opponents have blocked both measures for months. The Senate will try to cut off debate on each bill, a maneuver that requires the votes of 60 of the 100 senators.

Should either bill fail to get 60, it's dead, probably for years to come, since Republicans will control the House of Representatives for two years starting next month. Both measures were campaign promises of President Barack Obama, and neither is expected to get many GOP votes.

Many Republicans were outraged that the votes were even being taken. Sen. John McCain, R-Ariz., protested that the action is "clearly in keeping with the other side's political agenda."

The "don't ask, don't tell" bill is the better bet to move ahead. The House of Representatives passed the measure Wednesday by a largely partisan 250-175 vote.

The bill's Senate co-sponsor, Sen. Joe Lieberman, an independent from Connecticut, said he was confident he had the votes to end debate and move to a final vote, since at least three Republicans are expected to join virtually all the Senate's 56 Democrats and two independents who support it.

A previous Senate effort to end debate on the question failed, but this is a new version of the legislation and three Republicans say they're ready to back it now.

The Development Relief and Education for Alien Minors Act, aimed at changing immigration law, faces more opposition.

The bill would allow illegal immigrants younger than 30 who entered the U.S. before age 16, lived here for five years without committing serious crimes, graduated from high school and attended college or joined the military to be eligible for legal residency after meeting other criteria.

A study by the nonpartisan Congressional Budget Office estimated that the act would help 300,000 to 500,000 undocumented immigrants.

Obama and congressional Democratic leaders — who vowed to Hispanic voters during their 2008 campaigns that they'd change immigration laws — say that passing the act is the right thing to do and would help the nation's economy and military.

Antonia Cortese, the secretary-treasurer of the American Federation of Teachers, said on a conference call with supporters that Saturday's vote was perhaps the bill's last best chance.

"If the Senate fails tomorrow it is unclear we'll have another shot to pass this bill in the next few years," Cortese said.

DREAM Act opponents consider the bill a backdoor amnesty measure that rewards bad behavior. Roy Beck, the founder and executive director of NumbersUSA, which advocates strict immigration limits and enforcement of immigration laws, called on opponents to contact their senators. He warned that DREAM Act supporters would barrage senators over the next 24 hours.

Repeal of the 17-year-old "don't ask, don't tell" policy got a boost late last month when the Defense Department unveiled a study of more than 115,000 military personnel. Seventy percent said that ending the ban on gays serving openly would have a positive or neutral impact. Defense Secretary Robert Gates and Adm. Michael Mullen, the chairman of the Joint Chiefs of Staff, have urged repeal.