In the opening line of his poem “Rime of the Ancient Mariner,” Samuel Taylor Coleridge famously describes how the title character “stoppeth one of three” guests en route to a wedding.

 

President Obama isn’t an ancient mariner. But on Friday, the president “stoppeth one of three” Democratic New York House members from challenging Sen. Kirsten Gillibrand (D-NY) in next year’s Senate primary.

 

Lawmakers frequently use the Cannon Terrace outside the Cannon House Office Building on Capitol Hill for press conferences. Technically, lawmakers aren’t permitted to use it for campaign rallies. But that’s precisely what Reps. Carolyn McCarthy (D-NY), Carolyn Maloney (D-NY) and Steve Israel (D-NY) seemed to use it for last week in what appeared to be an effort to unseat Gillibrand.

 

McCarthy, Maloney and Israel made a powerful triumvirate when they arrived for the briefing. The threesome was mad about a loophole that permitted persons on the no-fly list to purchase firearms. And the trio fumed in their opposition to Sen. Kirsten Gillibrand (D-NY). In a shocking move earlier this year, New York Governor. David Paterson (D) plucked Gillibrand from relative obscurity in the House and appointed her to fulfill the unexpired term of Secretary of State Hillary Rodham Clinton.

 

The trinity of McCarthy, Maloney and Israel seemed like a force to be reckoned with when it came to contesting Gillibrand.

 

That is until President Obama swiped a page from Coleridge’s playbook and “stoppeth one of three.” In this case, Steve Israel.

 

Sources tell FOX that Sens. Chuck Schumer (D-NY) and Bob Menendez (D-NY) asked President Obama to implore Israel to not challenge Gillibrand.

 

A Democratic New York source says the senators solicited Mr. Obama’s assistance to help Gillibrand avoid a competitive primary in 2010. Menendez heads the Democratic Senatorial Campaign Committee, the panel charged with electing Democrats to the Senate. Schumer led that committee in years past.

 

It’s rare for a president to inject himself into statewide politics. And a host of New York political insiders with ties to several Democratic House Democrats say they’re angry that the president even got involved.

 

One source who spoke on the condition of anonymity said that “Israel was all set to go on Friday. This is messy.”

 

The source tells FOX that Israel was poised to announce his candidacy until the president intervened with a Friday afternoon phone call to clear the field for Gillibrand.

 

"This is a tough, heartfelt decision for me,” Israel said in a statement. “I have received encouragement to pursue this fight from all corners of our great state.”

 

Another source who spoke to FOX on the condition that their name not be used blasted Mr. Obama.

 

“What? You can’t have a primary? It’s decided in backroom deals?” asked the source. “What if someone told Obama he couldn’t have a primary and Hillary (Rodham Clinton) would just be the nominee? Where would he be? It’s an outrage.”

 

Gillibrand’s appointment to the Senate was controversial from the start. Even before Paterson tapped Gillibrand, McCarthy warned that she would challenge her in a primary if Gillibrand was the governor’s selection.

 

In particular, McCarthy, Maloney and Israel didn’t think Gillibrand paid her dues in the House yet. Others wondered whether the moderate Gillibrand would be viable in a statewide race. And there are questions about whether the senator can successfully court Wall Street after voting twice against last fall’s financial bailout package.

 

Despite speaking with Israel, President Obama did not make similar requests of McCarthy, Maloney, or even Rep. Jose Serrano (D-NY), another name mentioned as a possible candidate next year.

 

“I can’t imagine why (Obama) would do this,” said one source, referring to the president’s request to Israel to step aside. “I am sure that it will upset many (New York House) delegation members.”

 

In a statement, Menendez praised Israel as a “terrific Congressman” and said his panel looks forward to continuing working with (Gillibrand) to make sure she well-prepared for her race.”

 

McCarthy, Maloney and Serrano all declined comment Friday.

 

But they were more than willing to comment on Gillibrand last Wednesday. Particularly about Gillibrand’s positions on guns.

 

McCarthy was the most vocal.

 

“Don’t get me started,” said McCarthy with a heave of exasperation when asked about Gillibrand’s gun record. “Basically throw up an issue and she has changed her mind on it. And she did it record speed of one week.”

 

Gun violence is what prompted McCarthy to run for Congress in the first place. A gunman killed her husband and wounded her son during a shootout in the Long Island Railroad in 1993.

 

Firearms are a radioactive political issue. The National Rifle Association backed Gillibrand when she was in the House and represented a rural, upstate New York district. But her positions on gun control have evolved since her Senate appointment. In New York City, many view firearm restrictions as a tool to curb violent crime. That’s why it’s understandable that Gillibrand may amend her position since she represents a larger constituency. Gillibrand spokesman Matt Canter points out that “while gun violence was not an issue in her rural Congressional district, Sen. Gillibrand now represents many communities around the state that are affected by gun violence.” For instance, Canter points out that Sen. Chuck Schumer (D-NY) opposed agriculture subsidies when he was a Congressman just representing Brooklyn. But Schumer’s views on agriculture assistance changed once he moved to the Senate.

 

Canter says Gillibrand “always opposed gun violence and has always supported measures to keep guns out of the hands of criminals and other dangerous people.” He added that Gillibrand wants to work with her colleagues on this issue.

 

While McCarthy, Israel and Maloney all want to curb gun violence, they knew that the issue makes Gillibrand vulnerable. Particularly from one of them.

 

One of the best examples of senator’s potential peril on the Second Amendment issue came last week when. Gillibrand was one of only 29 senators to vote against an amendment prohibiting people from toting guns in national parks. And that gave McCarthy, Maloney and Israel the opening they needed to morph Wednesday’s Cannon Terrace press conference into a campaign rally.

 

“That was strictly a strong political move,” McCarthy said of Gillibrand’s vote.

 

Richard Cohen of National Journal asked “Will the three of you agree on which of you will run in a Democratic primary in New York?”

 

McCarthy responded that at the time, “no one so far has sad they’re actually running. But we’re thinking about it.”

 

At that point, Jonathan Allen of Congressional Quarterly jumped in.

 

“We’ll give you an opportunity right now,” Allen said.

 

The threesome laughed.

 

“You know, I think they just called votes!” said Israel.

 

And Carolyn Maloney then patted Carolyn McCarthy on the shoulder.

 

“Carolyn would make a great senator,” Maloney said of her fellow Carolyn.

 

Interestingly, while McCarthy criticized Gillibrand’s conversion on firearms restrictions, she also took credit for it. When asked whether she thought her gun control efforts sent Gillibrand a message, McCarthy responded “I hope so. I think that I’ve been very instrumental in changing her mind on the gun issue. And if I have to move to every other state and continue to be threatening to every Congressperson, then maybe I should do that.”

 

President Obama’s decision to body check Israel on Friday was a message to other Democratic Senate hopefuls: stay away from Gillibrand. And when a popular president like Mr. Obama inserts himself into a political primary, that means the likes of McCarthy, Maloney and Jose Serrano run at their own risk.

 

And if these lawmakers are serious about the Senate, perhaps the only option they have is what McCarthy suggested: move to another state and challenge somebody else.

 

- Chad Pergram covers Congress for FOX News. He’s won an Edward R. Murrow Award and the Joan Barone Award for his reporting on Capitol Hill.