(Reuters) - U.S. stock index futures were slightly lower on Thursday, a day after Wall Street closed at a record high, as investors fretted about possible obstacles to a Republican tax bill that the lawmakers are debating.
* A U.S. Senate tax-cut bill, differing from one already in the House of Representatives, was expected to be unveiled on Thursday, complicating a tax overhaul push and increasing scepticism on Wall Street about the effort.
* The S&P 500 has risen about 21 percent since the election of President Donald Trump a year ago, partly on the back of his promises to cut taxes and other business-friendly measures.
* However, Republicans have yet to score a major legislative win since Trump took office in January, even though the party controls both chambers of Congress as well as the White House.
* Investors were also concerned about the potential fallout from Democrat wins in regional U.S. elections this week - a signal for next year’s mid-term Congressional elections for Trump.
* With third-quarter earning season winding down, earnings for the quarter are expected to have climbed 8 percent, compared with expectations of a 5.9 percent rise at the start of October, according to Thomson Reuters I/B/E/S.
* Economic data at 8:30 a.m. ET (1230 GMT) includes weekly jobless claims, which are forecast having risen to 231,000 from 229,000 in the week ended Oct. 28.
* Wall Street closed at a record high on Wednesday as videogame makers rallied and Apple’s market value climbed above $900 billion.
* Shares of Roku (ROKU.O) soared 30 percent in premarket trading after the television streaming device maker’s quarterly results and guidance beat expectations.
* Perrigo (PRGO.N) rose 12.1 percent as the generic drugmaker raised its adjusted profit forecast.
* Dish Network (DISH.O) fell 1 percent as the satellite TV service provider’s third-quarter profit missed analysts’ estimates.
* Payments company Square (SQ.N) was down 3.2 percent, despite the company posting better-than-expected third-quarter results and raising its forecast.
Futures snapshot at 7:04 a.m. ET:
* Dow e-minis 1YMc1 were down 69 points, or 0.29 percent, with 41,821 contracts changing hands.
* S&P 500 e-minis ESc1 were down 8 points, or 0.31 percent, with 233,238 contracts traded.
* Nasdaq 100 e-minis NQc1 were down 22.25 points, or 0.35 percent, on volume of 35,676 contracts.
Reporting by Tanya Agrawal; Editing by Arun Koyyur