* Futures up: Dow 0.13 pct, S&P 0.12 pct, Nasdaq 0.20 pct
By Shreyashi Sanyal
Aug 28 (Reuters) - U.S. stock index futures rose slightly on Tuesday on hopes that a trade agreement between the United States and Mexico will go some way to averting a global trade war.
The benchmark S&P 500 and the Nasdaq indexes hit all-time highs on Monday after the two countries agreed to overhaul the North American Free Trade Agreement, putting pressure on Canada to remain part of the three-nation pact.
Canadian Foreign Minister Chrystia Freeland is expected to travel to Washington for talks on Tuesday. Her spokesman said Canada would sign only a new agreement that is good for the country.
U.S. President Donald Trump and German Chancellor Angela Merkel spoke by telephone and the two leaders "strongly supported ongoing discussions" on trade, according to the White House.
The early gainers in premarket trading included the trade-sensitive heavy machinery maker, Caterpillar, which was up 0.54 percent. Automakers General Motors, Ford and Fiat-Chrysler were up between 0.33 percent and 1.08 percent.
At 7:35 a.m. ET, Dow e-minis were up 34 points, or 0.13 percent. S&P 500 e-minis were up 3.5 points, or 0.12 percent and Nasdaq 100 e-minis were up 15.5 points, or 0.2 percent.
Tiffany & Co rose 3.7 percent after the upscale jeweler topped quarterly same-store estimates and raised its full-year profit forecast after strong sales in the Americas and Asia-Pacific regions.
Best Buy fell 5.5 percent after the electronics retailer's online sales growth slowed for a second quarter in a row and its current-quarter profit forecast missed estimates.
Xilinx climbed 2.6 percent after Baird upgraded the chipmaker's shares, citing an expected ramp-up in 5G-related shipments later this year.
Coty gained 5.9 percent after Morgan Stanley upgraded the beauty products maker's shares.
The Conference Board is expected to report its consumer confidence index for the month of August at 10 a.m. ET. (Reporting by Shreyashi Sanyal in Bengaluru; Editing by Shounak Dasgupta)