US President George W. Bush stepped to the right and left at the same time on immigration: courting conservatives with tough talk of sending the National Guard to the border and seeking to reassure moderates that a guest-worker program will be part of the mix.

"These are not contradictory goals," he declared in a televised address to the nation. Neither side seemed reassured.

Bush's speech from the Oval Office was an attempt to prod lawmakers and break a long-running political impasse, one that has social conservatives at odds with their business-community brethren as an election to determine the makeup of Congress approaches.

Raising the stakes in the immigration debate, Bush is proposing to use up to 6,000 National Guard troops along the border with Mexico. That idea was designed to appease the Republican right, particularly those supporting the House-passed immigration bill that would increase enforcement, call for constructing 700 miles of fencing and make being in this country illegally a serious crime.

At the same time, Bush is insisting, as he has since he was governor of Texas, on a guest-worker programme and a path to citizenship for many of the 11 million to 12 million illegal immigrants now in the country.

He challenged Congress to "honour the great American tradition of the melting pot, which has made us one nation out of many peoples," in addition to better defending the southern border.

That drew barbs from both sides of the political spectrum.

"It's amazing how tone-deaf this man is. This is the No. 1 issue that will lead to the takeover of Congress by Democrats," said longtime conservative activist Richard Viguerie. "The White House doesn't seem to have receivers. They only have transmitters."

Sen. Richard Durbin of Illinois, delivering a Democratic response, said Democrats were "willing to support any reasonable plan." But, he said, Democrats would not go along with "a plan cobbled together to win political favour".

Bush's intervention came as the Senate was debating the issue, and as the president seeks to rebuild support for a key element of his domestic agenda in a midterm election year that has seen an erosion of public support both for him and for Republican lawmakers in general. It is a particularly hot issue for Republicans in the border states of Texas, New Mexico, Arizona and California.

It is the first time Bush has spelled out his programme in such detail. And using the official Oval Office as the setting for his speech increases pressure on Republicans, who control both the House and the Senate, to make tough choices.

It also poses pitfalls for Democrats, who must decide whether to seek actively a bipartisan compromise with the president or block the effort in hopes of scoring political points.

The administration argues that the use of National Guard troops, whose ranks have already been thinned by deployments to Iraq, would only be temporary to support the Border Patrol while it builds up its own resources.

"Our party needs to be to be for a long-term solution for securing our border," said conservative Republican strategist Greg Mueller. "Immigration in the post-9/11 world is now a national defence and national security issue. To continue to succeed in elections, we must be the party of national security and national defence, and securing the border is top of the list."

"I think the conservative movement right now is somewhat frustrated and starting to let that be known," said Mueller. — The Associated Press