Editor's note: Julian E. Zelizer is a professor of history and public affairs at Princeton University's Woodrow Wilson School. His new book, "Arsenal of Democracy: The Politics of National Security -- From World War II to the War on Terrorism," will be published this fall by Basic Books. Zelizer writes widely about current events. Julian Zelizer says some of President Obama's political vulnerabilities have started to emerge. PRINCETON, New Jersey (CNN) -- June has been rough for President Obama. After experiencing enormous success during his first months in office, some of his political vulnerabilities have started to emerge. As Republicans begin to think about the 2010 midterm elections and moderate Democrats decide how they should vote on Obama's most ambitious initiative, health care, the White House must prevent these weaknesses from becoming debilitating.
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Julian Zelizer:  June has been a difficult month for President Obama
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He says divisions have grown among Democrats on gay rights, health care
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Zelizer says growing concern about deficit could blunt Obama's plans
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He says a new dip in the economy would be blamed on Obama, not Bush
@placeholder insist that without a public insurance option health care reform will fail in the long run.