By Ian Pannell
BBC Washington correspondent
US President George W Bush called Spain's incoming Prime Minister, Jose Luis Zapatero, this week to offer his congratulations.
President Bush lost a close ally with the victory of Jose Luis Zapatero in Spain
They exchanged polite words (there will be little love to lose in this relationship) and expressed mutual concerns about terrorism.
Apparently, the rather fundamental issue of Iraq wasn't mentioned. Many feel it should have been.
The view from America is that the two issues are now inextricably linked.
As the Washington Post reports, whatever the pre-war arguments, "al-Qaeda's tactics now have made explicit the connection between the continuing fight in Iraq and the overall war on terrorism".
Even Mr Zapatero seemed to acknowledge this reality in his interview with Spanish radio station Cadena Ser on Monday.
In a scathing criticism of American and British policy in Iraq, he said: "It hasn't generated anything but more violence".
Unless there is a United Nations mandate, Spain intends to withdraw its troops from Iraq at the end of June.
It is entirely likely that the UN could act. It would certainly save face in Washington and Madrid.
In terms of numbers, Spain's troop commitment in Iraq is fairly small. What the country offered was moral support that also lent some credibility to the administration's claim that it was leading a "coalition of the willing".
One concern in Washington is that other countries could follow suit or, more likely, that new sources of support might be cut off, further undermining attempts to internationalise the occupation.
This would leave America looking even more isolated than it already does.
Mr Zapatero said he would pull Spanish troops out of Iraq without UN action
Mr Bush has urged European allies to stick with him, saying: "It's essential that we remain side-by-side with the Iraqi people."
He has also been bashing the phones, talking to other world leaders, reassuring them of his commitment to the war on terrorism, no doubt looking for similar assurances in reply.
The other fear in Washington is the message that Spain's electorate may have sent to the terrorists.
The administration is too sensitive to say so publicly at this painful time, but there are real concerns here that the terrorists have just won an important strategic victory.
The question is what impact all this has on the willingness to prosecute the war on terrorism.
Don't forget this is also an election year in America and the impact of events in Spain could send political waves across the Atlantic.
The latest poll by Gallup indicates that the percentage of Americans who are very or somewhat concerned about terrorism has fallen from 58% after the September 11 attacks in 2001, to just 40% in
Even more interesting is the fall in the numbers who rate terrorism as the most important problem facing the US. That has dropped from nearly half to just 10% over the same period.
Spanish voters may have decided supporting the war in Iraq was too dangerous
In other words, September 11 is rapidly falling from the political horizon of most Americans, replaced by more traditional election-year concerns like the economy, jobs, healthcare and education.
The question is: What impact will the March 11 bombings in Madrid have on the US presidential race?
In the short-term it could generate greater concerns about terrorism per se. The candidate who stands to benefit most from that is the one who also happens to be the commander-in-chief, Mr Bush.
The Republican campaign team regard foreign policy, the war on terrorism and Iraq as the president's strengths.
They will argue that the attacks in Madrid prove three things: That the battle continues, that no person or country is safe, and that Mr Bush is the candidate with a proven track record in fighting terrorism.
Impact of attacks
The voters in Spain may have concluded that the costs of being an integral part of the "coalition of the willing" are too great.
The voters of America are unlikely to do the same. Indeed were there to be another attack in America, it would likely boost the president's ratings and credibility as a wartime leader.
However, it is unclear if the events in Madrid will increase the level of public concern about terrorism in the US.
Americans are more concerned about jobs and less about terrorism
As Gallup points out, "an analysis of data from the March 8-11 poll suggests little initial change in concern, as the results from polling done the night following the terrorist attacks were generally similar to those from the first three nights of interviewing".
Some Democrats will also argue that the attacks in Madrid lead to entirely different conclusions.
Many have argued that the war in Iraq was an unnecessary diversion from the war on terror - as opposed to an integral part of it, which the administration maintains.
These critics may well now say that the attacks in Spain are proof that President Bush's war on terrorism, rather than being successful, has actually led to more attacks, and that, rather than being defeated, al-Qaeda is both active and fatally effective.
The likely Democratic candidate for President, John Kerry, said: "As we saw again in Spain, real action is what is needed."
This Friday the president will deliver his assessment of the wars in Afghanistan and Iraq and promote what he sees as the success so far in the war on terrorism.
This is an issue that still works well for Mr Bush, but if there is any enduring lesson from recent events in Spain, it is that there is no guarantee that this will still be the case come November.