House Minority Leader Nancy Pelosi and Sen. Chuck Schumer are the two most influential Democratic voices on Capitol Hill.

They find themselves on opposite sides when it comes to support for President Obama’s Iran deal. Pelosi backs the accord. Schumer announced -- during Fox News Channel’s prime-time GOP presidential debate -- that he would oppose the agreement.

And regardless of where Pelosi, California, and Schumer, New York, stand on Iran, that might not make any difference to rank-and-file lawmakers struggling with their decision.

That’s because these sorts of votes are special to lawmakers. They are legacy votes. And often, a lawmaker simply has to come to terms with which way to go on their own. They look inside themselves. They seek counsel. They pray. And then they vote.

At the end of the day, it’s just about them.

Not only are Pelosi and Schumer the most prominent figures in the House and Senate Democratic caucuses, but they are both the odds-on favorites to be the Democrats’ top leaders on Capitol Hill when the 115th Congress convenes in January 2017 -- whether Democrats hold the majority or minority in either body.

Pelosi’s served as minority leader or House speaker since 2003. The retirement of Senate Minority Leader Harry Reid thrust Schumer to the top of the ladder as the heir apparent to the Nevada Democrat.

Schumer seemingly vaulted Senate Minority Whip Dick Durbin, D-Ill., for the post. Schumer has deeper ties to rank-and-file Democratic members and is a prolific fundraiser.

But that didn’t stop allies of President Obama and other Democratic activists from lighting up Schumer, questioning whether his opposition may be a disqualifying factor for him to emerge as the Senate’s leading Democrat.

“Senator Schumer siding with the GOP against Obama, Clinton, and most Democrats will make it hard for him to lead the Dems in '16,” brutally tweeted former longtime, senior White House adviser Dan Pfeiffer. “The base won't support a leader who thought Obamacare was a mistake and wants War with Iran.”

Former Obama speechwriter Jon Favreau tweeted:  “This is our next Senate leader?”

And then this sidewinder missile from MoveOn.org Political Action Executive Director Ilya Sheyman.

“Our country doesn’t need another Joe Lieberman in the Senate, and it certainly doesn’t need him as Democratic leader,” said Sheyman. “No real Democratic leader does this.”

Sheyman’s remark references former Independent Connecticut Sen. Joe Lieberman,  who lost the Democratic primary in 2006, sided with GOPers on many issues, endorsed Sen. John McCain, R-Ariz., for president in 2008, spoke at the Republican convention that year and came close to getting kicked out of the Senate Democratic Caucus.

Is this enough to imperil Schumer’s otherwise unchallenged bid to succeed Reid? Hard to say. Lots of time between now and that closed-door Democratic Caucus meeting just before Thanksgiving in November 2016.

After Reid announced his intention to retire, Schumer worked the phones and lined-up the necessary support to follow Reid within hours. Durbin certainly had interest but not the votes and wound up publicly backing Schumer for the gig. There are quarters of the Democratic Party that would like to see a woman in leadership, such as Sens. Patty Murray, Washington, and Elizabeth Warren, Massachusetts.

Liberals in the party would rejoice seeing Warren matriculate.

Leadership elections are often determined by what we’ll call “particle politics,” a series of small, infinitesimal factors at the subatomic political level.

A failure to support the Iran nuclear deal could develop as a contributing factor that moves the political electrons and protons when selecting the next Senate Democratic leader. Most importantly, there’s a lot of time between now and November of 2016. The nation will have already taken its vote for president before Senate Democrats huddle to choose Reid’s successor the fall after next.

When asked if Schumer’s defection could cast a pall on his leadership prospects, White House spokesman Josh Earnest noted it “is a question for Democratic senators.”

He added that the administration wouldn’t weigh-in on a leadership election. But Earnest cryptically added he “wouldn’t be surprised if members of the Democratic caucus would consider (Schumer’s) voting record.

Schumer was part of the 98-0 vote in 2001 that launched the U.S. war in Afghanistan following 9/11.

But more notably, Schumer was one of 77 “yeas” on the October 2002 roll call vote that authorized the war in Iraq. That particular vote for war has grown more toxic by the year -- infuriating the left and surfacing as an argument against Hillary Clinton’s fitness to become the potential Democratic flag bearer in 2016.

Many lawmakers of both parties now regret that vote - considering the morass that swallowed Iraq and the creation of ISIL.

Durbin and Murray were “noes” on the 2002 Iraq vote. Warren didn’t join the Senate until 2013.

Now back to the macro politics of the Iran deal and what Schumer’s decision means for congressional Democrats.

Some may perceive Schumer’s maneuver as an effort to provide air cover for Democrats who want to buck the deal. In other words, if one of the most-powerful Democrats in Congress is a no, then they can oppose Obama too and face few repercussions.

Certainly that phenomenon played out when just moments after Schumer’s declaration, New York Rep. Eliot Engel, the top Democrat on the House Foreign Affairs Committee, also announced his opposition.

But don’t read too much into this idea of Schumer running interference. Schumer was skeptical of the agreement from the start. He’s a Jewish, a New York Democrat from Brooklyn with a large Jewish constituency and is a staunch supporter of Israel.

His decision to buck Obama on Iran is newsworthy, but not a surprise.

The same with Engel. He’s long expressed reservations about the Iran package. And again, like Schumer, Engel is a Jewish, a New York Democrat who represents lots of Jewish voters and a longtime ally of Israel.

And other pro-Israel lawmakers with substantial Jewish voting blocs didn’t require Schumer’s inter-positioning to announce their opposition, too.

Rep. Steve Israel (D-NY) is the top-ranking Jewish lawmaker in the House, a member of the leadership and a lieutenant of Pelosi’s. He announced this week he’s opposed. Same with New York Rep. Nita Lowey, the top Democrat on the House Appropriations Committee.

Rep. Ted Deutch, D-Fla., followed suit. New York Democratic Reps. Grace Meng and Kathleen Rice will not support the president in this venture, either.

While Republicans are in lockstep in opposition to the agreement, Democrats are all over the map. Does this signal an ebb in support for Obama? Remember the president flopped earlier this year when he tried to convince Democrats to back a framework for a major trade treaty with 12 Asian nations.

Obama made extraordinary personal entreaties with lawmakers at the Capitol and the congressional baseball game on the eve of one vote -- only to suffer defeat.

He later succeeded.

It’s practically a foregone conclusion that both bodies of Congress will command the votes to reject the Iran pact and the president will veto that measure. What’s unclear is whether at least one body of Congress can sustain a veto. Overriding a veto requires a two-thirds vote of both houses of Congress -- 290 votes in the 435-seat House and 67 votes in the 100-seat Senate. A failure to override the veto means Congress didn’t demonstrate the sufficient legislative resolve to halt the package. The deal then goes through.

But overriding Obama’s veto would be an embarrassment of incalculable dimension on the world stage. The handicapping now is that the president’s firewall guarding against a veto override should hold. But it might be close.

“It’s not particularly surprising,” said Earnest of Schumer’s decision, also calling it “disappointing.” But Earnest didn’t think Schumer’s position would prevent Obama from mobilizing support to sustain the veto.

Two weeks ago, New York Rep. Jerry Nadler huddled with the president for about a half-hour prior to a session with him and fellow House Democrats about the Iran proposal. Nadler said Obama warned them about the potential geopolitical implications of rejecting the plan.

“It’s going to greatly lessen our credibility in dealing with anything in the future because people are going to say for a long time: ‘You can’t deal with (Washington) because who knows what they’re going to do.’ ”

That argument will resonate with some Democrats. The question remains will it be enough.

And that’s where Pelosi comes in.

Remember it was Pelosi -- who for good or ill -- engineered passage of The Affordable Care Act. Detractors may call it “ObamaCare.” But it was Pelosi’s acumen and pinpoint vote-counting that lugged that measure to passage in the House.

The nascent congressional leadership may be split now on this issue. Schumer one way. Pelosi the other. Earlier this year, Pelosi cast votes against the international trade agreement, bringing scores of Democrats with her to rebuff the administration’s desires.  Pelosi could ultimately take the helm on this one for the administration.

But it might not make any difference.

The votes for or against the Iran deal are likely the most-pivotal decisions in Congress since the vote to raise the debt ceiling in the summer of 2011. It’s right up there with the financial rescue package in the fall of 2008. It will rival the vote to go to war in Iraq in 2002.

These are votes of conscience. They’re very personal. And sometimes it doesn’t matter who says what to lawmakers about how they should vote. They’re the only ones with a voting card. They just have to get to yes or no on their own.