* Third-quarter GDP forecast rising at a 3.3 percent rate
* Trade seen subtracting from GDP; inventory boost expected
* Strong consumer spending growth anticipated
By Lucia Mutikani
WASHINGTON, Oct 26 (Reuters) - The U.S. economy likely slowed in the third quarter, held back by a tariff-related drop in soybean exports, but the pace probably remained strong enough to stay on track to hit the Trump administration's 3 percent target this year.
Gross domestic product probably increased at a 3.3 percent annualized rate, according to a Reuters survey of economists. While that would mark a slowdown from 4.2 percent in the second quarter, it would still well exceed the economy's growth potential, which economists put at about 2 percent.
"Given the fiscal stimulus, it's going to take a lot to derail this economy and I don't think that's going to happen anytime soon," said Ryan Sweet, senior economist at Moody's Analytics.
The economic expansion, now in its ninth year, is the second longest on record. The Commerce Department will publish its snapshot of third quarter economic growth on Friday at 0830 a.m. (1230 GMT).
The economy is underpinned by a $1.5 trillion tax cut and increased government spending. The fiscal stimulus is part of measures adopted by President Donald Trump's administration to boost annual growth to 3 percent on a sustainable basis.
Yet the government is also locked in a bitter trade war with China as well as trade disputes with other trade partners and the last quarter's slowdown mostly reflects the impact of Beijing's retaliatory tariffs on U.S. exports, including soybeans.
Farmers front-loaded shipments to China before the tariffs took effect in early July, boosting second-quarter growth. Since then, soybean exports have declined every month, increasing the trade deficit.
Economists estimate the widening trade gap chopped off almost 2 percentage points from GDP growth in the third quarter, which would reverse the 1.22 percentage point contribution in the April-June period.
However, the drag from trade was probably offset by faster inventory accumulation by businesses stockpiling before U.S. import duties, on mostly in Chinese goods, came into effect. Inventory investment is expected to have added as much 2 percentage points to GDP growth after slicing off 1.1 percentage points from output in second quarter.
"The big swings in trade and inventories between the second and third quarters are likely at least partially due to changes in activity associated with trade policy," said Daniel Silver, an economist at JPMorgan in New York.
Excluding the effects of trade and inventories, economists estimate GDP grew 2.8 percent in the third quarter compared to 4.0 percent in April-June.
Solid third-quarter growth is expected to keep the Federal Reserve on course to raise interest rates again in December, despite a recent tightening in financial market conditions brought about by a stock market sell-off and a rise in U.S. Treasury yields.
The Fed raised rates in September for the third time this year and removed a reference to monetary policy remaining "accommodative" from its policy statement.
Growth in consumer spending, which accounts for more than two-thirds of U.S. economic activity, is expected to have been strong in the third quarter after a 3.8 percent increase in the second quarter. Consumption has been supported in part by a tightening labor market, characterized by an unemployment rate that is near a 49-year low of 3.7 percent.
Business spending on equipment is also forecast to have supported growth in the third quarter. But headwinds are building. Higher interest rates are pressuring the housing market, businesses are struggling to find workers and the import tariffs are increasing manufacturing costs for companies, such as Caterpillar Inc, 3M Co and Ford Motor Co .
"We expect stronger growth in the first half of 2019 to give way to a gradual softening in the second half of the year as government spending, corporate profits and disposable income begins to decelerate as the benefits of the fiscal stimulus measures fade," said Sam Bullard, a senior economist at Wells Fargo Securities in Charlotte, North Carolina. (Reporting by Lucia Mutikani Editing by Tomasz Janowski)