By Richard Cowan
WASHINGTON (Reuters) - U.S. Senate Democrats plan to unveil a package of proposals this week to tighten domestic security in the wake of the mass shooting in California that killed 14 people and injured 21, according to a Senate Democratic source on Sunday.
One part of the plan, according to the source, attempts to make airports safe by beefing up Transportation Security Administration operations. Democratic Senator Bill Nelson has been pushing a bill to improve screenings of TSA employees.
Overall, the package would put Democrats out in front politically on an issue that is moving to center stage in Congress since the San Bernardino shootings.
Meanwhile, another Democratic aide said there is a strong possibility that the renewal of a range of U.S. intelligence programs could be included in a must-pass government spending bill lawmakers hope to complete in coming days.
Republicans have criticized Democratic President Barack Obama for not being tough enough against the Islamic State, which claimed responsibility for an attack in Paris last month.
The married couple blamed for the California attack, killed by police hours after the rampage, may have been followers of Islamic State, according to social media postings and law enforcement. But there is no evidence yet that they were working in coordination with the militant group.
Other elements of the Democrats' package will include initiatives already unveiled, including making it harder for people on "terror watch lists" to buy weapons and explosives.
That measure is opposed by the powerful National Rifle Association and many Republicans, who argue that innocent people, who have no intention of committing violent acts, can mistakenly end up on the watch lists.
Last week, Republicans blocked this proposal.
Another element, which Republicans are expressing support for, would tighten a visa waiver program enjoyed by travelers in 38 countries, many in Europe. It would require visa interviews for people in those countries if they have recently traveled to Iraq or Syria.
The aide said other provisions, which were not detailed, would be taken from bills that have been under consideration in the Senate Foreign Relations and Judiciary committees.
Democrats are in the minority in the Senate and Senate Majority Leader Mitch McConnell, a Republican, decides what bills come to the chamber for debate and votes.
Last month, the Republican-controlled House of Representatives voted to impose new restrictions on an Obama program aimed at bringing thousands of Syrian refugees to the United States. Critics in Congress said it would make it impossible to administer the program.
(Editing by Kevin Drawbaugh and Andrew Hay)