The Senate on Wednesday voted to open debate on the GOP’s tax overhaul bill, setting up a vote on final passage later this week. The party-line vote, 52-48, represented the largest step forward for the legislation thus far. The major point of contention among the GOP caucus is whether to include a so-called trigger mechanism that would mitigate the effects of the bill on the federal deficit. The legislation adds $1.5 trillion to the deficit over the next 10 years and relies on strong economic growth models to lessen that impact. In addition to slashing individual rates, the bill cuts the corporate tax rate to 20 percent and scraps the Obamacare individual mandate.