On his way to Maine this afternoon, President Bush is to visit a Raytheon Corp. plant in Andover, Mass., and pay homage to a missile that owes a lot to politics, and may owe still more in the future.

Throughout the Carter and Reagan years, the Patriot missile was an Army antiaircraft program lovingly nurtured by the Massachusetts and New Hampshire congressional delegations. Former House Speaker Thomas P. "Tip" O'Neill Jr., who is reported to have sometimes mixed up the Patriot with the Polaris submarine in calls to the Appropriations Committee in the 1970s, made sure the funds kept flowing.

Now Patriot has been modified to be an anti-missile weapon also, and its starring role in the Persian Gulf War is being used by Defense Secretary Richard B. Cheney to promote Bush's call for a Strategic Defense Initiative program that will shift its focus to providing protection from limited ballistic missile strikes.

"There's no way they're going to bury Patriot now," said Lawrence J. Korb, a Brookings Institution defense expert and former vice president of Raytheon, the missile's manufacturer.

Supporters of Patriot and other ground-based systems that defend against incoming tactical missiles rather than intercontinental strategic missiles find that somewhat ironic.

The development of the Patriot was slowed, they charge, because the Reagan administration diverted billions of dollars into research on futuristic space-based weapons with little chance to work. Some say that more advanced systems to destroy incoming tactical missiles would be ready now if SDI priorities had not been skewed.

During the 1980s, congressional backers of Patriot had to resort to backstage maneuvers in appropriations bills to keep research money flowing to Raytheon.

Sen. Warren B. Rudman (R-N.H.), whose state is home to 5,000 Raytheon employees, claimed some credit last week for the success of Patriot in the gulf war.

He said he agreed to add research money to defense spending bills after Raytheon executive Dennis J. Picard told him Patriot, originally envisioned for use against aircraft, could also shoot down missiles if the software could be perfected.

The well-publicized success of the Patriot in shooting down Iraqi Scud missiles attacking Israel and Saudi Arabia completely changed the political equation.

Raytheon now seems assured of continued funding for its work on an upgraded version of Patriot known as the Advanced Tactical Patriot. The Advanced Tactical Patriot, about which little is known, will be Raytheon's entry in a new generation of ground-based missile interceptors, which will have greater range, explosive power, speed and accuracy.

Under the administration budget recently sent to Congress, spending on these low-altitude systems would grow from $218.2 million this year to $600 million in 1992 and $725 million in 1993. But unlike other parts of the SDI budget that has already been sharply criticized in Congress, the ground-based systems appear to have considerable support.

Along with the Advanced Tactical Patriot, there is LTV Corp.'s Extended Range Interceptor (ERINT) and Arrow, a U.S.-Israeli project for which the U.S. government is paying 80 percent of the research and development costs.

ERINT, still in early development, is a small mobile fast interceptor with built-in radar guidance. The ERINT launcher reportedly can carry 167 missiles instead of the four missiles on a Patriot pad.

Arrow is a much larger system that is designed to provide area defense of Israel. It can intercept at greater distances than the Patriots, and reportedly has a powerful kinetic-energy warhead and could accommodate a chemical warhead.

Last year, Texas friends of Dallas-based LTV, fed up with what they considered inadequate funding of the ERINT program, flexed their muscles. Rep. Charles Wilson (D-Tex.) got the Appropriations defense subcommittee to agree to double ERINT funding to $103 million.

The $103 million for ERINT was preserved in the final bill. At the same time, pro-Israel members added money for Arrow, and New Englanders protected additional money for Advanced Tactical Patriot.

Congressional appropriators, concerned over the cost of developing all these systems, have been pressing the Pentagon to decide how it plans to use the various systems under development. Spokesmen for the contractors say, however, that the systems complement each other.

The first test firing of Arrow, in Israel last year, ended in disappointment when the range officer destroyed the missile after launch. Israeli officials say the problem resulted from a flaw in telemetry rather than the missile.

While Raytheon is at the early stages of this upgrading phase of the Patriot, a Pentagon source asserted that improvements now envisioned would take several years to complete and would not greatly improve the overall system. Raytheon officials did not return calls yesterday.

Officials and defense analysts continue to praise the Patriot's performance in the war. But televised pictures of damage in Riyadh, Saudi Arabia, and Tel Aviv resulting from recent Scud attacks have highlighted its limitations and could strengthen the case for improved systems that can intercept further away from targets and with a more lethal impact on the incoming warhead.

The Patriot is designed for "point defense" of sites such as airfields. Its warhead does not have enough explosive power to demolish its target and keep incoming missile parts from being scattered over a larger area such as a city.

As of Wednesday, the Pentagon counted 62 Scud launches, of which 32 were against Israel and 30 against coalition forces in Saudi Arabia. Of the 30 fired at Saudi Arabia, 23 have been intercepted by a Patriot missile.

Pentagon officials said they did not have a tally on Scud interceptions over Israel.