With little legislation to show for his months of low-key stewardship, House Speaker J. Dennis Hastert (R-Ill.) will warn GOP conservative dissidents this morning that Republicans risk losing control of the House unless members come together behind his agenda, according to close associates.

Alarmed by the crumbling of GOP unity over issues from spending and taxes to campaign finance and health care, Hastert has decided to take a much tougher line with rank-and-file Republicans who have stymied leadership efforts to pass important spending bills.

The associates said Hastert will tell Republican lawmakers this morning that the party cannot tolerate the kind of obstructionist tactics that tied up the House before the Memorial Day recess. While the speaker will allow Republicans a say on all important legislation -- and offer amendments to make their case -- he expects GOP members to fall in line once the leadership has decided on a course of action, they said.

The more assertive posture appears to be a tacit acknowledgment that Hastert's relatively laissez-faire approach has reached its limits, and that more aggressive leadership is necessary to keep the uneasy Republican congressional coalition from fracturing. While few lawmakers expect dramatic legislative initiatives this session, Republicans are anxious to pass routine bills and avoid another spending crisis that could provide Democrats with more ammunition during next year's critical campaign to argue that the GOP can't govern.

"Part of being a leader is being a little bit of an S.O.B," said Rep. Ray LaHood (R-Ill.), a close Hastert ally. "It's putting your fist on the table and saying, `Okay, folks, I've listened to everybody and here's what we're going to do.' "

The new strategy is fraught with risks, not the least of which is the uncertain reaction of independent-minded GOP conservatives. But the beleaguered speaker offered a preview of his new "tough love" style during a late afternoon gathering of House GOP leaders yesterday, and he intends to lay down the law when he meets this morning with the full Republican conference.

A senior Senate GOP aide, voicing his chamber's alarm over the growing chaos in the House, said the speaker "has got to come down hard on them and crack the whip."

Hastert was forced to postpone floor action late last month on several major fiscal 2000 bills -- including the defense authorization and spending bills for agriculture and the legislative branch -- in the face of a revolt by conservative activists. The conservatives are demanding deeper cuts than favored by the leadership and appropriators, in order to live within strict budget limits and avoid the temptation of dipping into the Social Security trust fund surplus later this year to finance more spending.

Rep. Tom Coburn (R-Okla.), a leader of the dissidents, has vowed to continue offering scores of amendments to tie up floor proceedings on spending bills until the leaders agree to freeze or slash most domestic programs.

"My inclination is to try to get the Republicans to do what they told the American people they will do and not spend any money above the caps and not spend one dollar of Social Security money," Coburn said before he and other conservatives were scheduled to meet with Hastert. "The strategy we're doing now will only assure there won't be a Republican majority."

Rep. Jack Kingston (R-Ga.) said Coburn and other conservative activists -- many of whom helped pressure the last speaker, Newt Gingrich, to step down -- have to realize that Republicans cannot afford to take such a hard line on fiscal matters when the party holds only a slim majority.

"Perfection does not happen with a five-vote majority," Kingston said. "Coburn's not going to get everything he wants."

Hastert will try to break the logjam this week, first by muscling through the $14 billion agriculture appropriations bill over Coburn's objections. He will propose revising the House's fiscal 2000 spending scheme to try to appease moderate Republicans and Democrats and improve prospects of passing bills. The tentative plan is to shift roughly $7 billion of defense funds and revenue from the projected sale of parts of the broadcast spectrum to key domestic programs that some lawmakers have complained are underfunded.

But Hastert also intends to "draw a line in the sand" by insisting that Congress stick with the spending caps, rather than dipping into the Social Security surplus to finance extra spending, according to a House GOP source. If the Democrats insist on more spending, they will have to take the heat.

Critics complain that Hastert is not addressing the more fundamental problem: the inadequacy of funding for domestic programs under the constraints of the 1997 balanced-budget agreement. Domestic spending would have to be reduced by nearly $16 billion next year merely to stay within the caps. Moderate Republicans and Democrats warn that without more money in the pot, it will be virtually impossible to pass all 13 annual spending bills and get the president to sign them.

Even with Hastert's plans for shifting some more funds to the domestic accounts, notes Rep. John Edward Porter (R-Ill.), chairman of the Appropriations subcommittee on labor, health and human services and education, "That simply means I would have to cut $9 billion instead of $11 billion."

"I think if we fail to come to grips in adjusting the caps in a reasonable way, given the war in Kosovo, we will end up with the same debacle we had last year, with the president [with added leverage] spending through the roof and no congressional controls," Porter said.

Some lawmakers and congressional aides cautioned that Hastert's new approach, combining toughness with a change in overall spending emphasis, faces other problems as well.

The proposal for beefing up domestic spending at the expense of defense already is drawing stiff opposition from House Appropriations Committee Chairman C.W. Bill Young (R-Fla.) and other defense hawks, who worry about military readiness in the throes of the Kosovo conflict.

Moreover, attempts by Hastert and the other leaders to get tough with the conservatives could easily backfire. House Majority Leader Richard K. Armey (R-Tex.) recently alienated several lawmakers by directly attacking Coburn for undercutting the leadership on the floor. Much will depend on the speaker's tone and his skill in attempting to defuse the controversy and get the House legislative machinery back on track.

Some of Hastert's allies are touting his presentation to the GOP conference today as his most important speech since the speaker's opening day address to the 106th Congress. Hastert will recall that Republicans turned to him for help last December, after the impeachment controversy took its toll on the party, and now he is asking for their unalloyed support as he leads the party into next year's campaign.

Former representative Bob Livingston (R-La.) had been tapped to succeed Gingrich as speaker, but then stepped aside the day the House voted to impeach Clinton after admitting to a number of extramarital affairs. Hastert, a little-known Illinois lawmaker who was then the chief deputy whip, was quickly drafted for the job.

"This is not a `take anybody to the woodshed' speech," said one Republican close to the Hastert, who predicted the new speaker would be firm, but not angry, in his talk. "This is, `We hang together or we hang separately.' "