PHOENIX - Approval of a comprehensive immigration plan with Republican votes would enable the party to once again compete for Latino votes here, Arizona's senior U.S. senator said Thursday.

It would not be "helpful" if the bipartisan proposal by the "Gang of Eight" is sidelined because Republicans who control the House - and have enough votes in the Senate to filibuster - refuse to go along, John McCain said Thursday.

"I think it's very obvious, as we know, the Republican Party has less support from the Hispanic community in the recent elections," he said in a joint telephone news conference with fellow Arizona senator and co-sponsor Jeff Flake. That clearly played out in the presidential race, when 71 percent of Latinos voted for President Obama.

But that does not mean strong Republican backing for the plan will suddenly make the GOP attractive to Hispanics, McCain said.

"If we pass this bill, I don't think we gain a single Hispanic vote immediately," he said. But that does not mean there will be no political payoff eventually.

"What it does is it puts us on a level playing field to compete for those votes," McCain said.

Those votes could make a difference. Nationally, the Pew Hispanic Center predicts Latinos will account for 40 percent of the growth among eligible voters in the United States between now and 2030, compared to 23 percent growth for non-Hispanic Anglos.

And estimates are Hispanics already make up 25 percent of the voting-age population in Arizona, though Hispanic turnout has not kept pace. In any event, Hispanics are likely to play an ever-increasing role in who gets elected in Arizona.

That still leaves the question of the political fallout if the plan falters and Republicans are blamed.

"I don't know, frankly, what happens if it fails because I'm not planning on it failing," McCain said. "But I know that if it succeeds, the scenario that I just described to you prevails."

Flake acknowledged the link between the issue and voter reaction.

"I generally think that good policy makes for good politics, and it's no different with immigration," he said. He did not address the question of whether a Republican-orchestrated defeat of the measure would undermine GOP chances in the future, saying only that both the policy and political arguments behind the measure are strong.

Separately, McCain said he believes if Congress adopts the measure, it likely eliminates the need for Arizona and other states to adopt laws similar to SB 1070.

That measure, approved in 2010, was aimed at allowing state and local police to detain and arrest those not in this country legally. Proponents said the state had to step in because of the failure of the federal government to secure the border.

McCain said one key element of this plan is $3 billion for border security, including new fencing, more Border Patrol agents and new technology developed in Afghanistan and Iraq to detect people crossing illegally. He said the legislation anticipates surveillance of 100 percent of the border with 90 percent "effective operational control."

That issue of border security is critical to get the support of Gov. Jan Brewer, who signed SB 1070.

Brewer is still studying the bill, but she has previously criticized other proposals for "comprehensive" immigration plans, saying she first wants the border secured, her press aide, Matthew Benson, said.

Both senators acknowledged that border security is a valid issue.

"It's important to assure the people of Arizona that we will not have a third wave," he said. Flake agreed.

"For those in Arizona who have borne the brunt of the federal government's failure to secure the border for so long, this is a welcome change," he said.