WASHINGTON (AP) — President Barack Obama's sweeping immigration executive orders cap a turbulent, six-year quest to make headway on a thorny issue that has at times put the White House at odds with some of its fiercest supporters.

To those who argue the actions are long overdue or don't go far enough, Obama pins the blame solely on Republicans who oppose broader legislation. But Obama himself has contributed to the delays, making political calculations that left legislative efforts languishing throughout his first term and paused the promise of executive action in his second.

In recent months, the protracted process has been aimed in part at finding more favorable political terrain to unveil measures that spare as many as 5 million people in the U.S. illegally from deportation. However, Obama's decision to ultimately wait until after the midterm elections to exert his presidential powers has only heightened the anger from victorious Republicans, who have suggested responding with everything from lawsuits to impeachment.

"The action he's proposed would ignore the law, would reject the voice of the voters and would impose new unfairness on law-abiding immigrants — all without solving the problem," said Sen. Mitch McConnell, the Kentucky Republican who is soon to become Senate majority leader.

Obama announced the executive actions Thursday after a fitful year of stops and starts. While the measures were widely welcomed by advocates, many said they had come far too late.

"It has been painful to see that it has taken so long because the politics get in the way all the time," said Ben Monterroso, the executive director of the advocacy group Mi Familia Vota.

As a presidential candidate, Obama told supporters he would "guarantee" an immigration bill within his first year in office. Yet his entire first term slipped by without a real effort to seek legislation.

The president's advisers say the economic collapse forced Obama to shift his priorities and spend much of his first year seeking to stem massive job losses. Still, the president pursued health care legislation before losing the Democratic control of Congress that would have given him his best opportunity to pass an immigration bill.

Immigration advocates quickly turned their attention to pressing Obama to halt deportations on his own — an authority he insisted he did not have.

"With respect to the notion that I can just suspend deportations through executive order, that's just not the case, because there are laws on the books that Congress has passed," Obama said in 2011.

Despite that assertion, Obama moved in 2012 to defer deportations for some young people who had been brought to the U.S. illegally as children. The action was viewed cynically by Republicans, who saw it as a ploy to bolster election-year support among Hispanics, the nation's fastest-growing voting bloc.

Obama ultimately carried more than 70 percent of the Hispanic vote in his resounding re-election win. In the days after his victory, he reached out to Hispanic activists and other supporters to assure them that he planned to make immigration reform his first piece of major legislation.

Anxious over their party's paltry support among Hispanics, some Republican leaders appeared ready to move on legislation too. A handful of GOP senators began working with their Democratic counterparts on a comprehensive bill that included a pathway to citizenship and enhanced border security.

But within weeks of the election, the White House's legislative strategy was upended by the horrific shooting at an elementary school in Newtown, Connecticut. Appalled by the deaths of 20 children, Obama thrust gun-control measures to the forefront of his legislative agenda. Despite the outrage over Newtown, a pared-down measure eventually failed in the Senate after three months of wrangling.

That brief delay in pursuing immigration legislation allowed conservative Republicans who opposed a broad bill to regain strength. While the Democratic-controlled Senate passed wide-ranging legislation in June, the GOP-led House repeatedly refused to take it up.

Again, advocates pressed the president to act on his own. But Obama appealed to them for more time, insisting there was still a window to pursue legislation.

It was June before the president acknowledged publicly that the prospect for legislative action was stalled and he would instead pursue executive actions before the end of the summer. But the joy and relief among immigration activists would be short lived.

Less than three months later, the president announced he was delaying unilateral measures until after the midterm elections. The move came in response to requests from nervous Democrats who feared the controversial actions could upend their chances of keeping control of the Senate.

Immigration advocates were furious. And the politically motivated move did nothing to help Democrats keep their Senate seats.

In January, Republicans will assume control of the chamber for the first time in Obama's presidency. They vow to launch an all-out fight to stop him from following through on executive actions that were six years in the making.

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Follow Julie Pace at http://twitter.com/jpaceDC