WASHINGTON – J Street, an organization founded to lobby for a two-state solution to the Israeli-Palestinian conflict, has joined the major leagues with its conference this week in Washington.For years, J Street has fought off a liberal reputation in order to gain a seat at the table with realists, tasked with the unfortunate job of ironing out stubborn details for a final-status agreement that can attain real peace for Israel in exchange for land.By sticking to their principal goal while reaffirming their commitment to Israel’s Jewish identity – and by condemning activists on the sidelines of their organization who protest the IDF and the legitimacy of Israel itself – J Street has become an important voice at an opportune time, speaking effectively in sync with Secretary of State John Kerry as he presses for an ultimate peace accord.“There is no contradiction between being progressive and being a supporter of Israel. None,” US Vice President Joseph Biden told the J Street audience to applause.But opening the conference, Justice Minister Tzipi Livni told the crowd not to abandon Israel’s security in pursuit of peace – and not to equate the crimes of suicide bombers and Hamas operatives with the “accidental” acts of IDF soldiers.“I don’t ask the world to turn a blind eye on our military actions. I ask them to judge us exactly according to their values,” Livni said.She, too, received ample applause for what Jewish World journalists billed as a “tough love” speech.At its gala dinner on Monday night, US special envoy to the peace process Martin Indyk said the US wanted nothing less than a final-status agreement, not an interim deal, that would end the conflict for good. And he warned that, without the establishment of a Palestinian state, Israel would soon face a stark choice between a democratic future and a Jewish one.It was the first time, in a short history only four conferences long, that J Street heard from such high-level speakers as the vice president of the United States and the US ambassador to an active, prioritized peace process. For their loyal followers, those engagements were a sign that years of work are starting to pay off, that their cause is historic and and that their moment may have finally arrived.That was the sense at the conference: That idealist slogans are well and good, but that an opportunity such as the talks that are now under way requires a serious political push that shows the breadth of their support and a serious appreciation for the sacrifices required of both sides.The primary task of the organization now is the launching of a $1 million campaign to mobilize Americans in support of a two-state solution.Such success will legitimize J Street’s work.