President Barack Obama pauses while talking about sequestration in the Eisenhower Executive Office building on the White House complex in Washington Feb. 19, 2013. (Charles Dharapak/AP)

President Obama’s legacy ultimately could be determined over the next few months by a series of showdowns — both with Republicans and, potentially, with fellow Democrats.

Guns. Immigration. Climate change. Debt and spending. The matters that Obama is either moving on or has promised to move on are the sorts of big issues that the two parties (and their presidents) have tangled with for decades and for which no easy solutions present themselves.

Solve them and Obama will write his name in the history books as one of the most influential presidents of the modern era. (Don’t forget he has already achieved a major overhaul of the nation’s health-care system.) Fail to find solutions and Obama likely will join the long list of presidents who promised to change Washington but ultimately came up short.

There’s little question of how Obama sees himself — particularly following his reelection victory in November. In a series of speeches since then, Obama has cast his proposals — on guns, the “fiscal cliff,” the sequester — as designed to help people achieve the American dream.

“It can feel like for a lot of young people that the future only extends to the next street corner or the outskirts of town, that no matter how much you work or how hard you try, your destiny was determined the moment you were born,” Obama said, discussing his proposal to curb gun violence in a speech in Chicago this month.

Later, he added, “We all share a responsibility to move this country closer to our founding vision that no matter who you are or where you come from, here in America, you can decide your own destiny.”

While Obama’s rhetoric about the grand aims he holds for his second term is clear, the political realities around these issues seem to point to the sort of small-bore solutions that he has long rejected.

Take guns.

There seems to be little expectation that an assault-weapons ban can be passed through Congress, a feat that even Bill Clinton, whose presidency was defined, largely, by its dearth of monumental challenges, was able to accomplish.

Obama has acknowledged as much; in his State of the Union speech his call to action was not for Congress to pass his proposals to lessen gun violence but rather to simply allow them to be voted on — something short of a historic stand on a controversial issue.

Ditto on the fight over how to reduce the country’s debt. The distance between the two parties over what mix of tax increases and spending cuts is the right one has been on stark display in the run-up to Friday’s sequestration deadline.

To say negotiations have broken down over how to avert the $1.2 trillion in automatic, across-the-board cuts assumes that they ever really began in earnest — which they didn’t. While most polling suggests that Obama enjoys the political upper hand on the issue, that won’t bridge the massive ideological divide that separates the two sides.

Movement on climate change is even more politically fraught, with even small-scale solutions somewhat unlikely to make it through Congress.

(Many congressional Democrats are still reeling from the House passage of a cap-and-trade measure in 2009, a piece of legislation that went nowhere and is blamed by some within the party for the loss of the chamber the following year.)

Of the second-term issues where Obama’s legacy will be made (or not), immigration reform seems to be the one with the highest probability of a “big” solution — given that a bipartisan group of senators is working on a compromise proposal.

Even there, however, passage of a major piece of legislation will be a heavy lift.

Obama wants to go big. But he oversees a legislative and political process that seems forever bent toward incrementalism.

And, as much as his allies insist that Obama can do little about the alleged intransigence of Republicans in Congress, he will almost certainly need to find a way to bend the other party (or at least a few dozen members) to his political will if he wants to leave the sort of mark on the presidency — and the country — that he so clearly desires to do.