Leading Democratic and Republican US senators have pledged to propel far-reaching immigration legislation through the Senate by this summer, providing a possible path to citizenship for an estimated 11 million people currently in the United States illegally.

The senators pointed towards changes in demographics, and particularly voting patterns amongst Hispanic voters, as providing an opportunity to establish broad bi-partisan support for the proposals made on Monday.

"The Republican Party is losing support of our Hispanic citizens," said John McCain, a Republican from the border state of Arizona and one of the eight senators working on the initiative.

Another member of the bipartisan group, Democrat Charles Schumer, said the public's attitude has changed.

"Four years ago they said 'fix the border.' Now they say they much prefer a comprehensive solution including a path to citizenship as well as fixing the border," the New York senator said.

The drive may pick up momentum on Tuesday when Barack Obama, the US president, lays out his vision for immigration reform during a speech in Las Vegas.

Obama is not expected to lay out a new plan, rather to restate his previously proposed policy changes, which are similar to those outlined in the senators' plan.

New proposals

Translating the aspirations expressed by the bipartisan group into an inevitably lengthy and complicated bill will itself be a major challenge.

In an attempt to build support among lawmakers, the senate proposal would couple immigration reform with enhanced security efforts aimed at preventing illegal immigration and ensuring that those foreigners here temporarily return home when their visas expire.

Under the proposal, undocumented immigrants would be allowed to register with the government, pay a fine, and then be given probationary legal status allowing them to work.

Ultimately, these immigrants would have to "go to the end of the line" and apply for permanent status. While waiting to qualify for citizenship, however, they would no longer face the fear of deportation or harassment from law enforcers if they have steered clear of illegal activity after arriving in the United States.

Missing were potentially controversial estimates about the future flow of immigrants under the legislation and the timeline undocumented immigrants would face for winning citizenship.

In light of growing Hispanic electoral power - and with US business demanding reforms to help them fill employment needs - leading Republicans have been urging conservatives to rethink both their positions and their rhetoric.

The Senate group included Republican Senator Marco Rubio of Florida, a favorite of the Tea Party movement who has helped garner support from influential conservatives.

Schumer said he hoped the Senate could pass legislation in late spring or early summer.

The last comprehensive revision of the United States' immigration law was in 1986. Numerous efforts since then have encountered stiff resistance, especially from the conservative wing of the Republican Party, which as recently as the Republican presidential primary races in 2012 opposed anything resembling an "amnesty" for undocumented immigrants.