Israel's most committed activists in the US, the members of the American Israel Public Affairs Committee, or AIPAC, have flexed their lobbying might once again at its annual Washington meeting.

After the 18,000 who gathered for this year's conference heard the speeches and the usual talking points, they spread across Capitol Hill to remind their senators and representatives why AIPAC is considered one of the most effective pressure groups in Washington.

But the past year has been wrenching for AIPAC.

The ascension of Donald Trump forced a group whose power lay in carefully refusing to choose sides between Democrats and Republicans to recalibrate.

When Trump as a presidential candidate told last year's meeting that Barack Obama "may be the worst thing that ever happened to Israel," winning cheers from the crowd, he violated that bipartisan understanding and forced a tearful apology by AIPAC's president.

AIPAC had its differences with Obama - standing awkwardly aside over his feud with Israeli Prime Minister Benjamin Netanyahu over Jewish settlement expansion in the occupied West Bank and fighting against Obama's nuclear deal with Iran.

But while AIPAC's leadership has been mockingly described as the American chapter of Netanyahu's Likud party (and Likud the Israeli wing of the US Republican party), it is also aware that Obama drew overwhelming support from Jewish voters.

And last year Hillary Clinton won 71 percent of the Jewish vote against Trump, slightly more than the 69 percent who voted for Obama in 2012.

'Exceptionally warm'

Speaking to the conference this year from Jerusalem, Netanyahu described his meeting with Trump in March as "exceptionally warm", in unspoken contrast to his relations with Obama.

He expressed appreciation for Trump's increased funding request for military aid in keeping with the 10-year, $38bn commitment Obama signed with Israel last year, the single largest pledge of military assistance in US history.

But the claim by Israeli ambassador to Washington Ron Dermer that "for the first time in many years, perhaps in many decades, there is no daylight between our two governments" may be a bit premature.

Trump may have heartened those in Israel who oppose a two-state solution to the Israeli-Palestinian conflict by straying from that long-standing US position and declaring he would be happy with whatever deal he could broker between them.

But in a interview last month, the president said that Jewish settlements in occupied territory "don't help the process" and did not think that "going forward with these settlements is a good thing for peace".

READ MORE: US-Israel relations - Is Trump backing down?

And after Trump promised AIPAC last year to relocate the American embassy from Tel Aviv to Jerusalem, his Vice President, Mike Pence, pulled back.

He told this year's assembly that Trump was only "giving serious consideration" to a move that would damage US relations with Jordan and other Arab states now currying favour with the new administration.

That followed the reaction to Trump's choice for ambassador to Israel, his former bankruptcy lawyer David Friedman, an outspoken opponent of a Palestinian state who is a financial backer of a Jewish settlement.

Even after Friedman fell back to the two-state solution and apologised for having once called liberal Jews worse than collaborators with the Nazis, his nomination was opposed by Reform Jewish congregations, the largest denomination in America.

But amid unconfirmed reports that the president may meet soon in Washington with Palestinian President Mahmoud Abbas, there's no assurance that Trump has been only paying lip service to reviving the negotiation process, as he's promised.

As for Iran, AIPAC and Trump still oppose the nuclear deal rhetorically but seem to have settled on ratcheting up sanctions to assure its enforcement rather than its undoing.

There is no indication that AIPAC has lost its clout in Washington.

But it may have tougher challenges maintaining a precarious political balance under Trump's volatile reign.