With her speech on immigration in Las Vegas on Tuesday, Hillary Rodham Clinton took a large step forward, up front and to the left of President Obama. That is a good place to be for a presidential candidate who proposes to get the stalled debate moving again, and to bring hope to the millions living here outside the law.

Mrs. Clinton defended a path to citizenship for those 11 million, and promised as president to take executive action — more broadly than Mr. Obama has — to defer the deportations of those who have strong bonds to the community through family and work. She also promised to make conditions “more humane” for immigrant detainees.

Mrs. Clinton noted that her call for a citizenship path sets her apart from any and all Republicans who are in, or likely to enter, the 2016 race. The same is true of her support for executive action. Senator Marco Rubio of Florida, a former advocate of sensible reform, had the sense beaten out of him by the Tea Party, and now seems to be seeking a vague provisional status for the undocumented — a long, difficult path to a temporary work permit. Jeb Bush, the former Florida governor, has been moderate in the past but is wobbly on citizenship, a nonstarter for many in his party. Whether he supports it for some immigrants, and which ones, under what conditions, is hard to pin down on any given day; like other Republicans hoping to survive the primaries, he is on his own tortuous path to a coherent position.

Like Mr. Bush, Senator Rand Paul of Kentucky speaks compassionately of immigrants at times, but his agenda seems limited to sealing the border and ending the 14th Amendment guarantee of citizenship by birth. Gov. Scott Walker of Wisconsin just wants every unauthorized immigrant to leave the country — and he wants to limit legal immigration, too. It’s early in the campaign, and the ground could always shift. Mrs. Clinton’s full-throated public commitment to expansive immigration action, while surprising and welcome, is only a few hours old. She may yet prove herself a staunch defender of immigrants’ rights, but only last fall she was dodging questions from the young advocates known as Dreamers with a discouraging non-answer: “Elect more Democrats.”