* Gov't has broad powers to expand, redirect spending (Updates after bill submitted)

By Magdalena Morales

BUENOS AIRES, Sept 15 (Reuters) - Argentina's governmentsent its 2011 budget to Congress on Wednesday without revealingdetails of the bill, which opposition lawmakers have vowed toblock if it low-balls inflation.

Recent budgets have included conservative estimates ofgrowth and revenue despite brisk economic expansion, lettingthe government spend "additional" income without congressionaloversight. They have also underestimated inflation, theopposition says.

Congress rubber-stamped the budget from 2003 through 2009,but President Cristina Fernandez lost her congressionalmajority last year. Political jockeying ahead of an October2011 presidential vote makes a stand-off even more likely.

"If the government budget is as deceitful as always, theywon't have the votes (to pass it)," leftist oppositionlegislator Claudio Lozano told Reuters.

Economy Minister Amado Boudou is due to outline the mainpoints of the bill in Congress on Thursday at 10 a.m. localtime (1300 GMT).

Ruling-party lawmakers say they will not accept majorchanges to the bill and have raised the possibility ofgoverning without a budget, which has happened in LatinAmerica's No. 3 economy during political or economic crises.

If talks on the budget end in deadlock, by law the previousyear's budget is extended automatically, which theoreticallycaps spending.

But ultimately, the government will be able to spend as itsees fit since it has so-called "superpowers" to redirectoutlays without congressional approval and can issue anemergency decree to acknowledge more spending after the fact.

Fernandez is expected to issue such a decree later thisyear to formalize additional spending, not accounted for in the2010 budget, which some analysts say could total as much as 60billion pesos ($14.98 billion).

Opposition lawmakers have moved to repeal thesesuperpowers, first passed in 2006, and also limit the scope ofemergency decrees. But they have not yet been able to get thesereforms passed by both houses of Congress.

"The proposal will include a significant underestimation offiscal revenue so that, once again, the government can use theextra resources according to their political needs," Analyticaconsulting group said in a report this week.

"This will be crucial in an electoral year," the reportadded.

INFLATION

The main sticking point in the budget is inflation, whicheconomists, opposition politicians and even some renegade statestatisticians say has been systematically underreported sinceearly 2007 for political gain and to reduce debt payments.

"Real" inflation is estimated at between double and triplethe official rate, and opposition legislators running theideological gamut have said they will not accept a budget thatestimates single-digit inflation for 2011.

The 2010 budget forecast 6.1 percent average inflation for2010, well below the 11.2 percent annual figure reported by thegovernment through July and the 20-plus percent price riseforecast by private economists.

The government defends official inflation data and isexpected to resist any efforts by the opposition to change theforecast for next year.

A deal could be reached if the government found allieswilling to pass the bill with minor changes only. Or oppositionlawmakers could try to push through their own version of thebudget, but they would not have the two-thirds of votes neededto override a presidential veto. ($1 = 4.0075 Argentine pesos) (Additional reporting and writing by Hilary Burke; Editing byNick Macfie)