WASHINGTON — Seeking swift action on immigration, President Barack Obama on Tuesday will try to rally public support behind his proposals for giving millions of illegal immigrants a pathway to citizenship, as well as making improvements to the legal immigration system and border security.

The president will launch his push in a campaign-style event in Las Vegas, a day after a bipartisan group of senators unveiled their own plan for addressing an issue that has languished in Washington for years.

Administration officials said Obama would largely endorse the senators’ efforts, though immigration advocates said they expected the president’s own proposals to be more progressive than the Senate group’s plan, including a faster pathway to citizenship.

The simultaneous immigration campaigns were spurred by the November presidential election, in which Obama won an overwhelming majority of Hispanic voters. The results caused Republican lawmakers who had previously opposed immigration reform to reconsider in order to rebuild the party’s reputation among Hispanics, an increasingly powerful political force.

Most of the recommendations Obama will make Tuesday are not new. He outlined an immigration blueprint in May 2011 but exerted little political capital to get it passed by Congress, to the disappointment of many Hispanics.

Obama “will certainly note today the promising signs we’ve seen in Congress, most specifically the bipartisan principles  put together by the group of senators that mirror his own principles,” White House spokesman Jay Carney told reporters aboard Air Force One en route to Nevada. “That is cause for hope. And what you’ll hear from the president today is how we need to take these initial positive steps and continue to move forward so that actual legislation is produced.”

The president was to make his pitch in Nevada, a political battleground he carried in November, in large part because of support from Hispanics in the state.

Nationally, Obama won 71 percent of the Hispanic vote, giving him a key advantage over Republican rival Mitt Romney.

Administration officials said the president would bolster his 2011 immigration blueprint with some fresh details. His original plan centered on four key areas: a pathway to citizenship for the 11 million illegal immigrants in the U.S., improved border security, an overhaul of the legal immigration system, and an easier process for businesses to verify the legal status of workers.

Administration officials said they were encouraged to see the Senate backing the same broad principles. In part because of the fast action on Capitol Hill, Obama does not currently plan to send lawmakers formal immigration legislation.

However, officials said the White House does have legislation drafted and could fall back on it should the Senate process stall. The officials spoke on the condition of anonymity in order to discuss internal strategy.

Carney said the president believes the package also should include recognition of gay couples where one partner is American and another is not.  

“The president has long believed that Americans with same-sex partners from other countries should not be faced with the painful choice between staying with the person they love or staying in the country they love,” Carney said.

Sen. John McCain called the issue a “red flag” in an interview Tuesday on “CBS This Morning.”

The Arizona Republican also said he didn’t think the issue was of “paramount importance at this time.”

“We’ll have to look at it,” McCain said. But he added that the highest priority is finding a “broad consensus” behind the immigration bill already being planned. He said the country must do something about 11 million people “living in the shadows.”

Obama’s previous proposals for creating a pathway to citizenship required those already in the U.S. illegally to register with the government and submit to security checks; pay registration fees, a series of fines and back taxes; and learn English. After eight years, individuals would be allowed to become legal permanent residents and could eventually become citizens five years later.

The Senate group’s pathway to citizenship for illegal immigrants already in the U.S. would be contingent upon securing the border and improving tracking of people in the U.S. on visas. Linking citizenship to border security could become a sticking point between the White House and lawmakers.

The Senate framework would also require those here illegally to pass background checks and pay fines and taxes in order to qualify for a “probationary legal status” that would allow them to live and work here — but not qualify for federal benefits — before being able to apply for permanent residency, a critical step toward citizenship. Once they are allowed to apply they would do so behind everyone else already waiting for a green card within the current immigration system.

Passage of legislation by the full Democratic-controlled Senate is far from assured, but the tallest hurdle could come in the House, which is dominated by conservative Republicans who’ve shown little interest in immigration reform.

The senators involved in formulating the immigration proposals, in addition to McCain, are Democrats Charles Schumer of New York, Dick Durbin of Illinois, Robert Menendez of New Jersey and Michael Bennet of Colorado; and Republicans Lindsey Graham of South Carolina, Marco Rubio of Florida and Jeff Flake of Arizona.

Several of these lawmakers have worked for years on the issue. McCain collaborated with the late Democratic Sen. Edward M. Kennedy on comprehensive immigration legislation pushed by then-President George W. Bush in 2007, only to see it collapse in the Senate when it couldn’t get enough GOP support.