US President Barack Obama made an outspoken pitch for a Senate bill on comprehensive immigration reform on Tuesday, branding those opposed to it insincere about fixing a badly broken system.
Obama has gently pushed the bill from behind the scenes for months, fearing his open support would swell the ranks of conservatives who see the bill as offering amnesty to illegal immigrants and who are determined to kill it.
But as the legislation faced a crucial test vote in the Senate, Obama waded into the fray, leveraging the political capital on the issue he won during last year's election campaign, particularly among Hispanic voters.
"This week, the Senate will consider a common-sense, bipartisan bill that is the best chance we've had in years to fix our broken immigration system," Obama said at an event at the White House.
The president also sought to disarm conservative Republicans -- even some who support immigration reform -- who argue that the bill should not be passed without tough new border security measures.
"I know there's a lot of talk right now about border security so let me repeat: today illegal crossings are near their lowest level in decades.
"If passed, the Senate bill, as currently written and as hitting the floor, would put in place the toughest border enforcement plan that America has ever seen. So nobody's taking border enforcement lightly."
Obama also took direct aim at the motives of lawmakers who are opposed to the bill, which was drawn up in the Senate by a bipartisan group of lawmakers known as the "Gang of Eight."
"There's no reason Congress can't get this done by the end of the summer," Obama said, but cast doubt on the motives of those wanting to block the bill.
"If you're not serious about it, if you think that a broken system is the best America can do, then I guess it makes sense to try to block it," he said.
"But if you're actually serious and sincere about fixing a broken system, this is the vehicle to do it, and now is the time to get it done.
"There is no good reason to play procedural games or engage in obstruction just to block the best chance we've had in years to address this problem in a way that's fair to middle-class families, to business owners, to legal immigrants."
The bill, which would give around 12 million illegal immigrants an eventual path to citizenship, will need 60 votes to pass the 100-seat Senate, and then face an uncertain ffate in the Republican-controlled House of Representatives.
Since their defeat in the 2012 presidential elections, some Republicans have shifted position and now support reform in the hope of winning over Hispanic voters, whose clout is expected to grow in future elections.