President Barack Obama sought to inject momentum into the push for U.S. immigration reform on Tuesday, urging lawmakers who were "serious" about the issue to support a Senate bill and highlighting the economic benefits of changing the system.

Obama, who won re-election last year thanks in part to strong support from Latino voters, has made immigration reform a top priority of his second term.

He had not given a major public address on the issue for some time, reflecting a White House strategy of not wanting to get in the way of the bipartisan bill's progress in the Senate.

Obama's speech on Tuesday was the first major departure from that strategy.

The Senate bill would authorize billions of dollars in new spending for enhanced border security and create new visa programs for high- and low-skilled workers in addition to providing a pathway to citizenship for the roughly 11 million undocumented immigrants currently in the country.

"If you genuinely believe we need to fix our broken immigration system, there's no good reason to stand in the way of this bill," Obama said at the White House, adding that the bill could be wrapped up by the end of the summer.

"If you're serious about actually fixing the system, then this is the vehicle to do it," he said.

The bill, which has broad support from Obama's Democrats, will need backing from some Republicans in order to give it momentum in the more conservative, Republican-controlled House of Representatives, where the pathway to citizenship provisions face more skepticism.

In a sign of the hurdles to come, House Speaker John Boehner, of Ohio, said he expected immigration reform to be law by the end of the year, but said the Senate measures to enforce the changes and secure the U.S. border with Mexico were insufficient.

And Senate Republican leader Mitch McConnell, of Kentucky, warned in a speech in the Senate: "In days ahead there will be major changes in this bill if it is to become law."

Boehner, the top Republican in Congress, told ABC television in an interview that aired on Tuesday: "I've got real concerns about the Senate bill, especially in the area of border security and internal enforcement of the system. I'm concerned that it doesn't go far enough."

Boehner added that reforming the nation's immigration system was his top legislative priority this year.

"I think by the end of the year we could have a bill," he told ABC. Asked if that bill would be one to also pass the Democrat-led Senate and be signed into law by President Barack Obama, Boehner said: "No question."

FIRST TEST

The first test for the immigration bill will come in the Senate on Tuesday when a procedural vote is held to formally bring the measure before the full 100-member chamber. Supporters of the bill are expected to get the 60 votes needed to clear the hurdle.

Many amendments are expected to be debated over the next few weeks as the Senate tries to pass its bill by July 4.

Republican Senator Marco Rubio, a Cuban-American lawmaker from Florida and one of the authors of the bill, on Tuesday said he would offer an amendment to tighten English language proficiency requirements for illegal immigrants who are trying to gain permanent residency in the United States.

Representative Chris Van Hollen, a Maryland Democrat and a member of his party's House leadership team, said on CNBC that it was unclear what kind of bill the House will be able to pass this year.

"I think Speaker Boehner would like to get some kind of comprehensive immigration reform through. The question is whether or not his caucus is willing to support that effort," Van Hollen said.

Van Hollen said that last week House Republicans pushed through passage of a measure that would resume deportations of children brought to the United States illegally by their parents.

Obama acted a year ago to temporarily suspend most of those deportations, noting that the children had no control over their illegal arrival into the United States and many of them had grown up here with little or no remaining ties to their native countries.

In his remarks on Tuesday, Obama also noted that border enforcement had improved dramatically under his administration's tenure and said immigration reform could only work if undocumented individuals had a chance to become citizens.

Leaders from business, labor, the religious community, and law enforcement joined Republican and Democratic lawmakers at the White House event.