NEW YORK — A group of top-ranking American ex-diplomats has come out strongly in support of the potential nomination of former senator Chuck Hagel for secretary of defense.

“Each of us has known the senator over the past 20 years and has found him invariably one of the best informed leaders in the US Congress on the issues of US national security,” read a letter of support released Thursday that was signed by the group of former officials, including several former ambassadors to Israel and other Middle Eastern countries.

Hagel, a decorated Vietnam veteran, millionaire entrepreneur and two-term Republican senator from Nebraska, is considered the front runner for the Defense post, according to reports late last week that are thought to have been leaked by the White House.

The reports have generated a growing chorus of opposition from conservatives who oppose Hagel’s foreign policy views; pro-Israel activists, including many Democrats, who object to Hagel’s past opposition to measures such as increased sanctions on Iran, labeling Hezbollah a terror organization, and more; and women’s groups who have urged President Barack Obama to appoint a woman to the position or risk seeing a cabinet without a single woman in its top posts.

On Thursday that chorus was joined by Sen. Marco Rubio (R-FL), who is reportedly concerned about Hagel’s past support for ending the US boycott on Cuba’s communist regime. Rubio’s spokesman Alex Conant told the Washington Free Beacon that “promoting democracy in Latin America is a priority for Senator Rubio, and he’s put holds on other administration nominees over the issue. If President Obama were to nominate Senator Hagel for a cabinet position, I’m sure we would have questions about Cuba positions.”

In response, the group of senior former officials have penned an open letter declaring, “We support, most strongly and without qualification, President Obama’s reported intention to nominate Senator Chuck Hagel to be the next secretary of defense.”

The signatories are:

- Nicholas Burns, former undersecretary of state for political affairs, ambassador to NATO and Greece

- Ryan Crocker, former ambassador to Iraq and Afghanistan

- Edward Djerejian, former ambassador to Israel and Syria

- William Harrop, former ambassador to Israel

- Daniel Kurtzer, former ambassador to Israel and Egypt

- Sam Lewis, former ambassador to Israel

- William H. Luers, former ambassador to Venezuela and Czechoslovakia

- Thomas R. Pickering, former undersecretary of state for political affairs, ambassador to Israel and Russia

- Frank G. Wisner, former undersecretary of defense for policy, ambassador to Egypt and India.

The letter responds to some conservative critics who have complained in recent days about Hagel’s opposition to the Iraq War.

“Senator Hagel’s political courage has impressed us all,” the diplomats write. “He has stood and argued publicly for what he believes is best for the United States. When he was attacked for opposing the war in Iraq as ‘unpatriotic,’ he replied, ‘To question your government is not unpatriotic – to not question your government is unpatriotic.’”

Hagel’s “credentials for the job are impeccable,” they insist.

“Time and again he chose to take the path of standing up for our nation over political expediency. He has always supported the pillars of American foreign policy – such as: a strong NATO and Atlantic partnership; a commitment to the security of Israel, as a friend and ally; a determination to stop the proliferation of nuclear weapons; and the defense of human rights as a core principle of America’s role in the world.”

Support for Israel is mentioned twice in the letter, an indication at the growing concern in pro-Israel circles about the nomination.

Hagel “has invariably demonstrated strong support for Israel and for a two-state solution and has been opposed to those who would undermine or threaten Israel’s security,” the former diplomats write.

“We can think of few more qualified, more non-partisan, more courageous or better equipped to head the Department of Defense at this critical moment in strengthening America’s role in the world. If he is nominated, we urge the speedy confirmation of Senator Hagel’s appointment.”