WASHINGTON, July 19 (JTA) — 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...