Five contenders for the 1984 Democratic presidential nomination drew much of the attention at the Texas Democratic state convention here this weekend, but the emotional highlight came on opening night with a speech by a young, liberal candidate running far down the ballot.

"We've had enough of this Reaganomics," shouted Jim Hightower, former editor of the Texas Observer and now Democratic nominee for state agriculture commissioner. "Reagamortis is setting in."

Hightower, an unabashed progressive and a powerful orator, had more than 5,600 delegates and alternates rocking back and forth between laughter and cheers as he ripped Reagan, Republican Gov. Bill Clements and the entire Republican Party in a speech brimming with one-liners.

"It's going to be more fun running against these little right-wing Republicans than choking chickens," Hightower said, his white, straw cowboy hat resting next to the microphone.

Hightower's well-received speech may represent more than a passing moment at a state convention.

Growth, migration and the presence of the first Republican governor in a century are pushing politics here more in line with the rest of the country, and while the state still looks conservative from a distance, there are interesting developments percolating just below the surface.

That was especially clear in Dallas this past weekend.

In a state that gave Ronald Reagan a landslide victory in 1980 and has sent a field full of Boll Weevils to Congress, the people with the biggest smiles were the liberals.

After years of domination by conservatives, the Democrats have put together a state-wide ticket that includes four candidates from the liberal wing of the party. All are currently favored to win in November.

"This is not the old Democratic establishment," said former representative Bob Krueger, who lost a bid for the Senate in 1978. "This is the new Democratic Party combined with old establishment figures."

The top of the ticket remains dominated by the party's conservative wing, with Sen. Lloyd Bentsen running for re-election, Attorney General Mark White the candidate for governor, and longtime Lt. Gov. Bill Hobby seeking another term.

But below that comes the youth movement. In a series of hotly contested Democratic primaries last spring, the most liberal of the candidates came up winners.

They include Rep. James Albon Mattox of Dallas as the nominee for attorney general; Ann Richards, a former county commissioner seeking to be the first woman elected state-wide since the 1930s, running for state treasurer; Garry Mauro, a former aide to Krueger who helped run George McGovern's campaign in Texas in 1972, running for land commissioner; and Hightower, who demolished the incumbent Democratic agriculture commissioner in the May primary.

The four "down-ballot" candidates have given the Democrats not only their most balanced Democratic ticket in recent memory, but a unity among the party faithful that has been rare in this traditionally one-party state.

"This is the healthiest political climate I've seen in Texas in my lifetime," said Bernard Rappaport, an insurance executive and supporter of liberal Democrats nationally.

Texas politics is the history of warring Democratic factions, with the monied conservatives usually running over the under-funded liberals.

Liberals have won occasionally; one was Ralph Yarborough, elected to the Senate in the 1950s. But in 1970, party conservatives reasserted themselves and he was defeated by Bentsen in a bitter primary campaign.

In 1978, the conservative-liberal split cost the Democrats the governor's seat. The progressive wing won the Democratic gubernatorial primary, but the divisions were so deep that many Democratic voters stayed home.

Clements won a surprise victory by 17,000 votes. More than anything else, Clements' election began to change Texas party politics.

Today, many conservatives who call themselves Democrats are supporting Clements. In fact, the governor and Bentsen share many of the same contributors -- and have been careful not to offend one another this year. Another victory by Clements, the brash founder of a huge oil-drilling firm, could turn many of those Democrats into permanent GOP voters, creating a Republican Party of substantial strength for the first time in modern Texas history. That is the reason politicians of both parties believe so much is at stake in Texas this fall.

"If the Republicans get turned back, they lose everything. They're back to square one," said retiring Democratic land commissioner Bob Armstrong. "If we lose, it's a two-party state for sure, not probably."

But the election of Clements also unlocked the Democratic Party to a younger generation of candidates whose views had long been held down by a succession of conservative Democratic governors. Now, the presence of these candidates on the Democratic ticket gives Democrats hope of beating Clements and sweeping all the state-wide races.

Hightower argues that Texas is neither a conservative nor a liberal state. "There is a genuine thread of the Texas populist spirit here, of pocketbook populism," he said.

National Democrats identified as liberals still have trouble in Texas. In the 1980 Democratic primary, Sen. Edward M. Kennedy got only about one-quarter of the vote. But Hightower and the others on the state-wide ticket here hope to prove to Democrats in the rest of the country that Texas is not permanent Republican territory in national elections and that progressives have a future in conservative parts of the country.

"We're showing how you get elected," Hightower said.