As President Bush enters the immigration debate, keep several facts in mind.

First, large majorities believe the president’s immigration policy is a failure — just like his Iraq policy, his energy policy, his economic policy and almost about every other policy he has pursued. Only 25 percent approve of Bush’s performance on immigration, while 61 percent disapprove.

Second, Bush’s newfound desire to protect our border has more to do with politics than policy. When some 500,000 illegal aliens crossed our border in 2003 and his approval rating averaged 60 percent, the president did not act. When another 500,000 illegal aliens entered in 2005 and he had a 46 percent approval rating, he did not act. Only now that his approval rating has sunk to 31 percent has Bush attempted to act decisively. Coincidence? I don’t think so.

Indeed, not only did the president fail to act earlier, he refused to act earlier. In 2004 Congress mandated the hiring of 2,000 more Border Patrol agents, but the President and the Republican Congress refused to provide the funding to hire them all.

There are only two explanations for the fact that under this president apprehensions of illegal immigrants have dropped by 30 percent. Or for the fact that, under Bush, audits of employers suspected of hiring illegal aliens have dropped by 75 percent from the Clinton years. Either border security has been a low priority for this administration or it is simply not competent — or a little of both.

While, in the words of Senate Minority Leader Harry Reid (D-Nev.), “it’s about time” Bush acted, the reason he is forced to call up overburdened National Guard troops is that he refused Democrats’ request to increase the number of Border Patrol agents. And, of course, the reason the Guard is overburdened is Bush’s failure to plan adequately for his lengthy occupation of Iraq.

Third, focusing on border protection will resonate strongly with public opinion. Eighty percent favor increasing the number of agents patrolling the border, with just 15 percent opposed. Although when the question involves use of the military at the borders support drops to 55 percent, Americans want to secure our borders. This desire is not motivated solely, or evenly mainly, by anti-immigrant bias but rather by respect for law and by the realization that a porous, unsecured border is a welcome mat for terrorists.

Nevertheless, fourth, while voters do want secure borders, they also recognize we are a nation of immigrants and reject Republican attempts to demonize immigrants and Latinos. Given a choice between the House Republican approach of deporting all illegal immigrants as criminals and allowing earned legalization for those who work, learn English and pay taxes, voters prefer earned legalization by 72-25 percent.

Fifth, Republicans are hopelessly divided on this issue, and a president at 31 percent will be unable to unite the warring factions within his own party.

This only adds to the palpable angst emanating from the White House. There are only two policy pronouncements George Bush could make that have any chance of enhancing his public image. Sending troops to the border was one. The other is bringing troops home from Iraq.

He has now done the first. Will it succeed in increasing the president’s approval ratings? Only time will tell. But if we don’t see a meaningful increase in Bush’s ratings in the wake of this announcement, his chances of improving his standing before the election are very limited indeed.

There is no doubt Monday night’s announcement was political. The only question is how good the politics will turn out to be.

Mellman is president of The Mellman Group and has worked for Democratic candidates and causes since 1982, including Sen. John Kerry (D-Mass.) in 2004.