WASHINGTON — With most polls showing Democrat Mark Udall and Republican Cory Gardner running almost even in their battle for the U.S. Senate, Gardner in recent weeks has tried a new tactic to break the deadlock.

He’s gone global, and attacked Udall on foreign policy.

It’s an unusual maneuver, as foreign policy rarely has much bearing on House or Senate races. Adding to the difficulty is Udall’s experience in that arena, especially on intelligence matters.

But with Election Day less than two months away and President Barack Obama’s approval numbers on foreign policy in the basement, Gardner has broadened his criticism of Udall to include both terrorism and the crisis in the Middle East.

The gambit has risks, not the least of which is showcasing the difference in worldviews between the two candidates. But Gardner has committed to this line of attack, going so far as to compare Udall’s position to one of betrayal.

In an interview last week with The Denver Post, Gardner blasted Udall for not describing the activities of the Islamic State of Iraq and the Levant (ISIL) — whose members recently beheaded two U.S. journalists — as an “imminent threat” to American safety.

“The only person who doesn’t believe (the Islamic State) is an imminent threat is Mark Udall,” Gardner said. “To say they are not an imminent threat is betraying the security needs and safety of our country.”

For his part, Udall has condemned the violence committed by Islamic State militants. But the first-term senator has stopped short of calling the U.S.-designated terrorist group an immediate danger to the U.S. homeland — a reticence that reflects his overall caution in overextending American might at home and abroad.

“It is very clear that ISIL presents a very serious threat to U.S. interests and allies in the Middle East, and the group’s actions have left no doubt that it’s going to take both brains and brawn to defeat them,” Udall said recently at a hearing held by the U.S. Senate Armed Services Committee, of which he is a member.

Clear dividing line

While the rhetorical difference between “imminent” and “serious” may seem slight, Udall’s reluctance to go further represents a clear dividing line between Udall’s political philosophy, which includes early opposition to the Iraq War, and that of his Republican rival.

National polls have shown widespread disapproval of Obama’s handling of foreign affairs: Only 35 percent of Americans supported Obama’s approach to the world compared with 58 percent who disapproved, according to an average of recent polls tallied by the website Real Clear Politics.

“President Obama’s poll numbers generally and (on) foreign policy and terrorism (in particular) have tanked fairly dramatically, and so to the extent that Cory Gardner can tag Sen. Udall as weak on national security and weak on terrorism,” the better it is for him, said Matthew Dallek, an expert on political history at George Washington University.

But there’s a risk, too — for both candidates — in advocating too strongly for foreign intervention or overselling the danger posed by overseas threats, he said. Liberal Democrats have raised concerns about another costly adventure in the Middle East, and there’s a vocal wing within the Republican Party with doubts as well.

“There is a deep frustration and a deep weariness of our inability as a country to impose our will on events,” Dallek said. “Look at all our resources and all the U.S. blood and treasure that have been spent on Iraq and Afghanistan, and look where we are now.”

In making his case about the immediate threat posed by the Islamic State, Gardner pointed to reports coming from the Pentagon about U.S. citizens fighting alongside militants in the region.

Gardner also cited the case of a young Colorado woman who pleaded guilty this month to a charge of trying to help the Islamic State and related terrorist organizations. Shannon Maureen Conley, 19, was arrested in April at Denver International Airport as she was preparing to travel to Syria.

The Islamic State and its members have “the time and the space and the organization to operate,” and are a “direct threat” to the U.S. and its allies, Gardner said.

To deal with the danger, Gardner said Obama needs to develop a “clear strategic mission,” but offered few other specifics.

Like Udall, Gardner opposes the deployment of U.S. ground troops in Syria and Iraq to combat the Islamic State. Both men also voted in support of legislation last week that would arm so-called “moderate” opponents of the terrorist group.

Reached by phone, Udall reiterated his assertion that the Islamic State is a “serious” concern. But he added that the “intelligence doesn’t support (the premise that) ISIL has the capacity to attack us today.”

“Congressman Gardner wants to argue about semantics, but my focus is on getting the job done,” Udall said.

While Udall does not see an imminent risk to the U.S. homeland, he says the country still must strike quickly against Islamic State militants before they get that chance.

“Intelligence does support (that) they are a serious threat if we don’t face them down now,” he said.

That Udall isn’t sounding the alarm as loudly as Gardner is partially a function of Udall’s role in the Senate. He sits on the Armed Services Committee as well as the Select Commitee on Intelligence, where members have access to classified documents often not available to other lawmakers. (Gardner is a member of the House Energy and Commerce Committee.)

Trying to explain his position has gotten Udall in trouble on the campaign trail. At a recent debate with Gardner, Udall said the U.S. shouldn’t be “impulsive” following the beheadings of two U.S. journalists at the hands of Islamic State captors.

“I can tell you, Steve Sotloff and James Foley would tell us, ‘Don’t be impulsive. Horrible and barbarous as those executions were, don’t be impulsive. Come up with a plan to knock ISIL back,’ ” Udall said.

Gardner criticized Udall for speaking for the two dead Americans, and Udall issued an apology.

War skeptic

Even so, the line captures Udall’s general reluctance toward military intervention overseas. His father, the late U.S. Rep. Morris Udall, D-Ariz., was an early critic of the Vietnam War. And Mark Udall was similarly skeptical of the Iraq War — voting in 2002 against the force resolution sought by then-President George W. Bush.

Udall, then a member of the House, was one of 133 members to vote against the resolution, saying ahead of the vote that it “could take us to a costly full-scale war with Iraq too quickly when we have not exhausted every other means of preventing it.”

He recalled that debate when asked about the danger posed by Islamic State fighters.

“There’s a real irony right now,” Udall continued. “We were told 12 years ago that we needed to go into Iraq because there were terrorists there with weapons of mass destruction.”

And while that claim was proved false, Udall said now there is a real threat in Iraq that requires U.S. intervention. However, he added, the burden to confront the Islamic State shouldn’t fall on Washington alone. Arab nations must “do their part,” he said.

“For too long, Arab countries (have been) both arsonists and firemen; it’s time for them to step up and defeat ISIL.”

But U.S. attempts to assemble a coalition to face the Islamic State — or rally other countries for a variety of other causes — is hamstrung, Udall said, by the continued existence of the military detention facility at Guantanamo Bay.

“Its existence makes it harder to work with our allies,” Udall said.

Gitmo differences

Here is another sharp divide between Udall and Gardner: For several years, Udall has pushed Congress and the White House to close the facility, which Udall considers both a “recruiting tool for extremists” and “a symbol around the world of an America that flouts the rule of law.”

Instead, Udall has raised the idea of trying the detainees in either military commissions or civilian courts — though he has lauded the effectiveness of the U.S. justice system in dealing with terrorism.

“Sooner rather than later, this facility will have to close and no matter where the detainees are transferred, Sen. Udall believes they must face justice in the highest security facilities possible,” a Udall spokesman said.

Gardner had a more direct take. He supports keeping Guantanamo Bay open as long as necessary, even if that means the detainees are never released or ever face a civilian court. He does, however, support trying the detainees in military tribunals.

“Sen. Udall wants to read them the Miranda rights,” Gardner said. “I want to keep them out of this country.”

The two lawmakers are less apart on their defense of civil liberties for U.S. citizens — though Udall has played a more prominent role in advocating a check on Big Brother intrusions. Gardner acknowledged Udall’s activism during a recent debate.

“I’ve made sure that I’ve stood for privacy and the rights of the people time and time again,” Gardner said. “And I appreciate Sen. Udall’s work on this issue as well.”

Udall frequently has criticized the data collection methods used by the National Security Agency. And he co-authored legislation in 2013 that would bar the bulk collection of Americans’ records as well as add more oversight to the secretive Foreign Intelligence Surveillance Court, which largely has rubber-stamped requests by U.S. authorities to undertake surveillance operations against suspected foreign threats.

“We need to end the NSA’s collection of millions of innocent Americans’ private phone records and focus on the real problem: terrorists and spies,” Udall said last year in introducing the measure — though Congress continues to debate its main provisions.

Gardner, meanwhile, backed related legislation in the House last year that would end the NSA’s blanket collection of phone records, according to supporters.

He said Congress needs to help ensure a “balance” between security needs and privacy concerns.

Mark K. Matthews: 202-662-8907, mmatthews@ denverpost.com or twitter.com/ mkmatthews