Spain's lower house of Parliament has approved a hotly contested constitutional amendment that will force the government to keep its future deficits very low.

The change approved Friday is aimed at reassuring markets over Spain's debt-heavy public finances and now goes to the Senate for a vote next week.

The vote tally in the 350-seat chamber was 316 in favor and five against.

A handful of angry lawmakers from leftist and small regional-based parties opposed to the amendment walked out before the vote.

The Senate is also expected to pass to the amendment because it was supported by the country's two dominant parties, the ruling Socialists and opposition conservative Popular Party, in a rare show of unity designed to ward off contagion from Europe's debt crisis.