washington | Sen. John Kerry (D-Mass.) has learned in the last year to walk the walk on Israel and Jewish issues.

The nagging worry for Israel’s government is that he might break into a run.

Political insiders see the single substantive difference between the Middle East policies of President Bush and the presumptive Democratic nominee is not in their content, but in their pace.

On his official Web site, Kerry says peace will “only be viable if U.S. engagement in this process is active, constant and at the highest levels.”

That’s a clear shot at Bush: Except for a short period in the summer of 2003, the Bush administration has largely left the pace of Middle East peace to Prime Minister Ariel Sharon.

Kerry’s champing at the bit worries Israel’s leaders. No matter how pro-Israel he is, they say, an American president who takes an active, involved role in Middle East peacemaking inevitably veers into confrontations.

Still, it is a measure of how far Kerry has come with Jewish voters that his stated difference with Bush over the depth of U.S. involvement in peace-brokering is the single issue raising questions about Jewish support for his campaign.

Many believe Kerry has caught up with Bush on pro-Israel statements, reinforced the natural advantage any Democrat has on domestic issues and opened a new front — with his brother’s emotion-laden visit to Israel last week — to combat a perceived empathy problem.

“You’ll see Kerry doing extraordinarily well among Jewish voters on election day,” said Steve Grossman, a former president of AIPAC-American Israel Public Affairs Committee who during the primaries switched allegiances to Kerry from former Vermont Gov. Howard Dean.

“John Kerry has as good a record on Israel as anyone has ever had; his public statements and his commitment to American values and Jewish values are unequivocal,” said Grossman, who also served as chairman of the Democratic National Committee.

Kerry has striven to address perceived missteps early in his campaign, when he said of Israel’s West Bank security barrier, “we don’t need another barrier to peace” and named as possible peace brokers President Carter and former Secretary of State James Baker — figures many Jews view as anti-Israel.

“Kerry has matched the rhetoric of Bush on all the issues,” said Abraham Foxman, national director of the Anti-Defamation League and one of a group of Jewish organizational leaders who met with Kerry in January to address concerns that rose during the primaries. “Now it’s a question of trust. What Bush has going for him is that he has acted on these things; Kerry still needs an opportunity.”

Kerry says he, like Bush, would leave the lead to Israel, but Israeli officials say — when the microphones are off and the pens and pads are put away — that his repeated commitment to accelerating the peace process worries them.

Sharon, for his part, has not made much of a secret of his preferences. “In all these years, I have never met a leader as committed as you are, Mr. President, to the struggle for freedom and the need to confront terrorism wherever it exists,” Sharon told Bush when they met in April.

He snubbed Kerry during that visit, as did his foreign minister, Silvan Shalom, last month. Israeli leaders usually make a point of meeting with both candidates when visiting during an election year. Sharon, did, however, meet Kerry’s brother, Cameron, in Israel last week.

In the past few months, Kerry has marched in lockstep, at least in words, with every one of the White House pro-Israel strides. He immediately matched Bush’s historic recognition of some Israeli claims to West Bank land and rejection of any right of Palestinian refugees to return to Israel.

Modifying his positions on Israel issues poses its own political perils, leaving an opening for the Bush-Cheney campaign to accuse him of flip-flopping.

“Support for Israel’s fight against terrorism needs to be above politics, and Kerry’s comments are another reminder of why voters can’t trust him,” Bush-Cheney campaign spokesman Steve Schmidt said recently after Kerry condemned the world court ruling.

Kerry spokesmen counter by pointing to Bush’s own evolution on the barrier over the last year, from opposition to support.

Kerry has not neglected domestic issues, even though he easily trumps Bush in that arena among the majority of Jews who express concern about post-Sept. 11 infringements on civil liberties, support abortion rights and oppose a constitutional amendment to ban gay marriage.