WASHINGTON - President Barack Obama will pitch his bid to revamp the U.S. healthcare system as a way to control big insurance company rate increases when he releases his healthcare plan on Monday, the White House said.

The Democratic president will propose giving the U.S. government new power to block health insurers from attempting excessive premium hikes in the plan to be posted on the White House website at 10 a.m. EST (1500 GMT), an administration official said.

The White House is gearing up for a nationally televised bipartisan healthcare summit on Thursday, which it hopes will help seize back control of the debate on how to overhaul the $2.5 trillion U.S. medical care system.

The new program to give the Department of Health and Human Services more authority over rate increases by private insurers and create a new Health Insurance Rate authority had not been included in Democratic healthcare overhaul bills reached after months of debate in the House of Representatives and Senate.

The White House has been targeting health insurers with particular vehemence as it made its case for the revamp, seeing corporate profits as a relatively easy target for public anger in the face of flagging voter interest in one of Obama's top domestic policy priorities.

Administration officials had said rising insurance rates would be the backdrop of Thursday's meeting. The White House has pointed to premium increases of up to 39 percent for some California customers of WellPoint Inc.'s Anthem Blue Cross plans to make its case about the need for a major healthcare reform.

As bad as things are today, they'll only get worse if we fail to act. We'll see exploding premiums and out-of-pocket costs burn through more and more family budgets, Obama said on Saturday.

WellPoint has said the higher prices reflect growing costs and are in line with competitors. The company, stung by the criticism, said it would postpone the increase by two months.

POLITICAL PRESSURE FOR SOME RESULT

With unemployment hovering near 10 percent, Obama's Democrats are under pressure to produce results on something before elections in November in which the entire House and more than a third of seats in the Senate will be up for grabs.

White House officials said they expected Obama's plan -- the first formally proposed by the White House during the year-long healthcare debate -- would combine the best features of the House and Senate bills.

Those bills are broadly similar. Both would extend coverage to many of the 46 million Americans now without insurance and impose restrictions on insurance companies like requiring them to cover people with pre-existing medical conditions.

Obama's proposal is also expected to require most Americans to carry health insurance.

Congressional Republicans, who have remained solidly united in opposition to the healthcare bills, have called on Democrats to scrap both and start over with a far less sweeping agenda.

Obama asked Republicans to publish their own overhaul program before the meeting, but there has been no indication they will do so, with Republican aides saying party leaders will continue to offer their own ideas, not a plan.

We believe that we think a better way to go is to, step by step, move in the direction of dealing with the cost issue, targeting things like junk lawsuits against doctors and hospitals, interstate insurance competition, small association health plans, Mitch McConnell, the Senate Republican leader, said on Fox News Sunday.

There are a number of things you can do without having the government try to take over one-sixth of the economy.

Analysts have criticized Obama for relying on Democrats in Congress to promote the healthcare revamp, and Thursday's conference could put his stamp firmly on it in the eyes of the public. Although Obama's approval ratings have dropped to about 50 percent, polls show Americans still view him more favorably than either Republicans or Democrats in Congress.

If the summit is marked by partisan gridlock, it could give the Democrats an excuse to combine the House and Senate measures as a privileged budget reconciliation bill, which only needs a simple 51-vote majority to pass the 100-member Senate, bypassing Republican opposition.

(Editing by Philip Barbara)