Its crunch time for the Comcast-Time Warner Cable merger. It is not going smoothly as the two companies had hoped. The Federal Communications Commission (FCC) seems unlikely to rubber-stamp their approval.

Thursday will be a crucial day for the merger, as Comcast will meet with officials from US Department of Justice (DOJ) to discuss and pleads its case for the giant cable company's $42.5 billion bid for Time Warner Cable, The Guardian reported.

Last week, the justice department was set to recommend blocking the merger deal because it would affect a lot of consumers. The Comcast-Time Warner Cable merger would create a company that controls two-thirds of the broadband market in the United States, according to Bloomberg.

As Comcast prepares for Thursday's meeting, six US senators urged the FCC and DOJ to block the Comcast-Time Warner Cable merger. According to Ars Technica, the senators including Al Franken, Bernard Sanders, Edward Markey, Ron Wyden, Elizabeth Warren and Richard Blumenthal all signed the written letter, which was addressed to FCC Chairman Tom Wheeler and Attorney General Eric Holder.

"We believe that Comcast-TWC's unmatched power in the telecommunications industry would lead to higher prices, fewer choices, and poorer quality services for Americans-inhibiting US consumers' ability to fully benefit from modern technologies and American businesses' capacity to innovate and compete on a global scale," the senators said on their letter.

Sen. Franken reminds consumers that the Comcast-Time Warner Cable merger would control 57% of the nation's broadband connections. And that would give them unprecedented gatekeeper power, both to content companies and to consumers.

Moreover, Comcast agreed to a whole bunch of mitigating concessions when they were permitted to buy NBCUniversal in 2011, and they didn't exactly make good on all of those.

Franken also pointed out that Comcast's opposed devotion to net neutrality - that devotion that was mandated for them in the NBCU merger, and that disappeared in the light of actual, stringent regulations.

Meanwhile, Franken is hopeful with FCC's Net neutrality, to help disapprove the Comcast-Time Warner Cable merger.

The Net neutrality rules include provisions preventing carriers from providing speedier Internet access to content providers that pay extra for it. The National Cable Telecommunications Association, a trade group that counts Comcast and Time Warner Cable among its members, is among the parties that have filed suit to block Net neutrality, CBS News noted.

"The FCC's decision on net neutrality has given me new hope, with a loud enough movement -- with enough people like you organizing online, calling your members of Congress, and writing to the FCC and DOJ -- we might just be able to win another uphill battle," Franken said.

"We might just be able to stop the Comcast-Time Warner Cable merger, before Comcast gains even more power to pad their profits at consumers' expense," Franken concluded.